JP5282268B2 - Image forming apparatus and fixing temperature control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device equipped with a fixing device for suppressing power consumption by controlling properly a fixing temperature by utilizing effectively remaining heat of a fixing material. <P>SOLUTION: This image forming device includes: a heating part 81 for heating a fixing member 82; a temperature detection part 83 for detecting a temperature of the fixing member 82; a temperature control part 85 for controlling the fixing temperature by switching on/off the heating part 81 based on the detected temperature; a prediction part 86 for assuming a period in which a lower limit temperature necessary for fixing until finish of a print job is secured without switching on the heating part 81 and the fixing temperature becomes a temperature near the lower limit temperature when the print job is finished in consideration of transition of the fixing temperature when continuing the print job in the state where the heating part 81 is switched off virtually, and predicting a start timing of the period; and a prohibition part 87 for putting the heating part 81 into the switched-off state by prohibiting control by the temperature control part 85 from the predicted start timing until finish of the print job. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus including a fixing device, and more particularly to a technique for suppressing power consumption by appropriately controlling a fixing temperature.

Some electrophotographic and electrostatic recording image forming apparatuses can form images on any of a plurality of types of recording sheets such as plain paper, thick paper, thin paper, and an OHP sheet.
In such a fixing device provided in the image forming apparatus, a lower limit temperature required for fixing in order to obtain a stable fixing property on any recording sheet and due to an unexpected temperature drop such as undershoot during temperature control. The temperature of the fixing material such as the fixing roller and the fixing belt is controlled so that the temperature becomes somewhat higher than the lower limit temperature so that fixing failure does not occur without securing the toner.

On the other hand, there is an image forming apparatus having a power saving mode in which the heat source of the fixing device is turned off in the standby state. Normally, the heat source is turned off when printing is finished and the final recording sheet passes through the fixing device.
However, even if the heat source is turned off after the final recording sheet has passed through the fixing device, the temperature of the fixing material does not drop easily, and if the remaining heat of the fixing material is effectively used, further reduction of power consumption can be expected.

For example, in Patent Document 1, the position of the transfer material on the conveyance path is detected, and at a predetermined timing after the detection, and before the rear end of the transfer material being passed is discharged from the fixing unit, An image forming apparatus that fixes a toner image with residual heat by cutting off the power supply is disclosed (first embodiment, etc.), and it is described that excessive power can be reduced (paragraph 0049, etc.).
Further, for example, Patent Document 2 discloses an image forming apparatus that detects the end of image data to be printed and stops power supply to a fixing device (specific example 1 or the like). One sheet or a plurality of sheets In the case of printing image data that spans over, it is described that the fixing at the blank portion can be eliminated on the last page, thereby eliminating wasteful power consumption and extending the life of the halogen lamp (paragraph 0034, etc.) .

Further, for example, Patent Document 3 discloses an image forming apparatus that changes the temperature to a temperature lower than the target temperature when the blank portion at the rear end of the image reaches the fixing nip portion (Claim 4 or the like), which is given by a heating member. It is described that curling can be prevented from occurring at the end portion of the transfer material due to excessive heat amount (paragraph 0029 and the like).
JP-A-8-171307 JP 2003-251884 A JP 2005-266440 A

  However, in the above-mentioned Patent Document 1, during the passage of the transfer material, the energization to the heating means is always cut off at the same timing without considering the difference in the amount of heat taken by the transfer material depending on the type of the transfer material. In order to obtain a stable fixing property to the material, the conditions cannot be made so severe, and there is still room for reducing electric power. If the conditions are too severe, fixing defects may occur in a transfer material with a large amount of heat.

Moreover, in the said patent documents 2 and 3, it suppresses electric power supply in a blank part and a blank part, Comprising: The said residual heat is not utilized.
The present invention relates to an image forming apparatus including a fixing device capable of suppressing power consumption by effectively utilizing the remaining heat of the fixing material and appropriately controlling the fixing temperature, and a method for controlling the fixing temperature in the fixing device. The purpose is to provide.

In order to achieve the above object, an image forming apparatus according to the present invention is a recording sheet in which a pair of rotating members are arranged close to each other in a state where a fixing nip is formed between them and an unfixed toner image is formed in the fixing nip. Is an image forming apparatus for fixing a toner image to a recording sheet by heating while being heated at a pressure and a fixing temperature, and heating means for heating at least one of the pair of rotating bodies, and heating by the heating means Detecting means for detecting the temperature of the rotating body or a temperature corresponding to the temperature of the rotating body, and the fixing by turning on and off the heating means based on the temperature detected by the detecting means during a print job The temperature control means for controlling the temperature, and the heating means in consideration of the transition of the fixing temperature when the print job is continued with the heating means virtually turned off. A prediction that predicts the start timing of the period assuming a period in which the lower limit temperature necessary for fixing is ensured until the end of the print job, and the fixing temperature is close to the lower limit temperature at the end of the print job. And a prohibiting means for prohibiting the control by the temperature control means and turning off the heating means from the start timing predicted by the prediction means to the end of the print job , the prediction means,
Holding means for holding a table that defines the number of remaining prints in a print job for each recording sheet type as an index for predicting the start timing, obtaining means for obtaining the recording sheet type, and a table held in the holding means Extracting means for extracting the number of remaining prints corresponding to the type of recording sheet obtained by the obtaining means, counting means for counting the number of remaining prints in the print job, and the number of remaining prints counted by the counting means A determination unit that determines whether or not the number of remaining prints extracted by the extraction unit is equal to or less, and a notification that notifies the prohibition unit when it is determined by the determination unit that the number of prints has decreased to the start timing. And the prohibiting means receives a notification from the notifying means. Characterized in that that a prohibited control by the temperature control means to the state of turning off the heating means.

In order to achieve the above object, according to the fixing temperature control method of the present invention, a pair of rotating bodies are arranged close to each other so as to form a fixing nip therebetween, and an unfixed toner image is formed in the fixing nip. A method for controlling a fixing temperature in an image forming apparatus for fixing a toner image on a recording sheet by passing the recording sheet while heating at a pressure and a fixing temperature, wherein the image forming apparatus includes: Heating means for heating at least one, and the control method detects a temperature of a rotating body heated by the heating means or a temperature corresponding to the temperature of the rotating body; and the detecting step during a print job A temperature control step for controlling the fixing temperature by turning the heating unit on and off based on the temperature detected by the control unit; and virtually turning off the heating unit In consideration of the transition of the fixing temperature when the print job is continued in this state, the lower limit temperature required for fixing is ensured until the end of the print job without turning on the heating means, and the fixing temperature at the end of the print job. Predicting a period in which the temperature is near the lower limit temperature and predicting the start timing of the period, and controlling by the temperature control step from the start timing predicted by the prediction step to the end of the print job. prohibited to look contains a prohibition step of the state of turning off the heating unit, wherein the image forming apparatus, a further table defining the remaining number of prints in the print job for each type of the recording sheet as an index for predicting the start timing Holding means for holding, and the predicting step obtains the type of the recording sheet. An obtaining step, an extraction step for extracting the remaining number of prints corresponding to the type of the recording sheet obtained by the obtaining step from the table held in the holding unit, a counting step for counting the number of remaining prints in the print job, A determination step for determining whether or not the remaining number of prints counted in the counting step is equal to or less than the remaining number of prints extracted in the extraction step; A notification step for predicting and notifying to the prohibition step, the prohibition step prohibiting the control by the temperature control step and turning off the heating means when receiving the notification from the notification step. Features.

With the configuration described in the means for solving the problem, considering the transition of the fixing temperature when the heating unit is turned off, the heating unit is turned off before the end of the print job, and the print job is finished as it is. Since the fixing can be performed, the remaining heat of the fixing material can be effectively utilized and the fixing temperature can be appropriately controlled.
Therefore, power consumption can be suppressed.

  Further, the heated rotating body can be similarly applied to a roller or a belt, for example. However, the rotating body is a belt, and the belt is wound around the heating roller and the fixing roller. In such a case, there is a slight distance between the heated portion and the fixing nip, and according to the above configuration, the start timing can be predicted in consideration of this distance, so more power consumption Can be suppressed.

Furthermore, since the heating means can be turned off before the end of the print job at different timings for each type of recording sheet, errors due to different amounts of heat taken away by the difference in recording sheets can be eliminated, It is possible to appropriately control the fixing temperature by effectively utilizing the residual heat of the fixing material.
Therefore, power consumption can be suppressed.

Here, the table that is held before Symbol holding means, the sheet type of the recording sheet, and by the sheet size can also be characterized in that defining the remaining number of prints.
As a result, it is possible to eliminate an error due to a difference in the amount of heat taken due to a difference in the paper type and sheet size of the recording sheet.

In the image forming apparatus according to the present invention, a pair of rotating members are arranged close to each other in a state where a fixing nip is formed between them, and a recording sheet on which an unfixed toner image is formed is heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet while passing through, a heating means for heating at least one of the pair of rotating bodies, and a temperature of the rotating body heated by the heating means, Detection means for detecting a temperature corresponding to the temperature of the rotating body; and temperature control means for controlling the fixing temperature by turning on and off the heating means based on the temperature detected by the detection means during a print job. In consideration of the transition of the fixing temperature when the print job is continued with the heating unit virtually turned off, the print unit is turned on without turning on the heating unit. Predicting means for predicting the start timing of the period assuming a period in which a lower limit temperature necessary for fixing is ensured until the end of the print job and the fixing temperature becomes a temperature near the lower limit temperature at the end of the print job; And a prohibiting means for prohibiting the control by the temperature control means from the start timing predicted by the means to the end of the print job and turning off the heating means, the prediction means comprising a duty ratio of the heating means A measuring unit for measuring the number of prints remaining in a print job according to a duty ratio as an index for predicting the start timing, and a measuring unit for measuring from the table held by the holding unit. Extracting means for extracting the number of remaining prints corresponding to the duty ratio, and printing Counting means for counting the number of remaining prints in the job, determination means for determining whether the number of remaining prints counted by the counting means is less than or equal to the number of remaining prints extracted by the extracting means, A notification means for predicting the start timing and notifying to the prohibition means when it is determined that the start timing has been reached, and the prohibition means prohibits the control by the temperature control means upon receiving a notification from the notification means it shall be the said to the above heating means off.

As a result, the heating means can be turned off before the end of the print job at different timings depending on the duty ratio. It is possible to eliminate errors due to the difference in the amount of heat generated, and to effectively control the fixing temperature by effectively utilizing the residual heat of the fixing material.
Therefore, power consumption can be suppressed.

Here, in the image forming apparatus, the measuring unit measures the immediately preceding duty ratio every time one sheet is printed, and the extracting unit extracts the remaining number of printed sheets every time one sheet is printed, and the counting unit Can count the remaining number of prints every time one sheet is printed, and the determination unit can determine each time one sheet is printed.
As a result, since the latest duty ratio can be measured and determined every time one sheet is printed, the determination accuracy is high and power consumption can be further suppressed.

In the image forming apparatus according to the present invention, a pair of rotating members are arranged close to each other in a state where a fixing nip is formed between them, and a recording sheet on which an unfixed toner image is formed is heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet while passing through, a heating means for heating at least one of the pair of rotating bodies, and a temperature of the rotating body heated by the heating means, Detection means for detecting a temperature corresponding to the temperature of the rotating body; and temperature control means for controlling the fixing temperature by turning on and off the heating means based on the temperature detected by the detection means during a print job. In consideration of the transition of the fixing temperature when the print job is continued with the heating unit virtually turned off, the print unit is turned on without turning on the heating unit. Predicting means for predicting the start timing of the period assuming a period in which a lower limit temperature necessary for fixing is ensured until the end of the print job and the fixing temperature becomes a temperature near the lower limit temperature at the end of the print job; And prohibiting means for prohibiting the control by the temperature control means and turning off the heating means from the start timing predicted by the means to the end of the print job, the prohibiting means from the start timing to the print job wherein said that to resume the control by the temperature control means when in a paused state until the end.
As a result, in the case of the temporary stop state, a problem that the fixing temperature is too low to cause a fixing failure is avoided, and the user is not made to wait when the print job is resumed.

In the image forming apparatus according to the present invention, a pair of rotating members are arranged close to each other in a state where a fixing nip is formed between them, and a recording sheet on which an unfixed toner image is formed is heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet while passing through, a heating means for heating at least one of the pair of rotating bodies, and a temperature of the rotating body heated by the heating means, Detection means for detecting a temperature corresponding to the temperature of the rotating body; and temperature control means for controlling the fixing temperature by turning on and off the heating means based on the temperature detected by the detection means during a print job. In consideration of the transition of the fixing temperature when the print job is continued with the heating unit virtually turned off, the print unit is turned on without turning on the heating unit. Predicting means for predicting the start timing of the period assuming a period in which a lower limit temperature necessary for fixing is ensured until the end of the print job and the fixing temperature becomes a temperature near the lower limit temperature at the end of the print job; Means for prohibiting the control by the temperature control means from the start timing predicted by the means to the end of the print job, and for turning the heating means off. until the end of the job, when the number of prints is increased, it characterized by resuming the control by the temperature control means.
As a result, when the number of prints increases, a problem that the fixing temperature is too low to cause a fixing failure is avoided.
In the fixing temperature control method according to the present invention, a pair of rotating members are arranged close to each other so as to form a fixing nip therebetween, and a recording sheet on which an unfixed toner image is formed is pressed and fixed on the fixing nip. A method for controlling a fixing temperature in an image forming apparatus that allows a toner image to be fixed to a recording sheet by passing while heating at a fixing temperature, wherein the image forming apparatus heats at least one of the pair of rotating bodies. A detecting step for detecting a temperature of the rotating body heated by the heating means or a temperature corresponding to the temperature of the rotating body, and a temperature detected by the detecting step during a print job. And a temperature control step for controlling the fixing temperature by turning the heating means on and off based on the printing, and printing with the heating means virtually turned off. Considering the transition of the fixing temperature when the job is continued, the lower limit temperature necessary for fixing is ensured until the end of the print job without turning on the heating means, and the fixing temperature is set to the lower limit at the end of the print job. A prediction step of predicting the start timing of the period assuming a period of temperature close to the temperature, and prohibiting control by the temperature control step from the start timing predicted by the prediction step to the end of the print job, The image forming apparatus further includes a holding unit that holds a table that defines the number of remaining prints in a print job according to a duty ratio as an index for predicting the start timing. The prediction step includes a measurement step for measuring a duty ratio of the heating means. An extraction step for extracting the remaining number of prints corresponding to the duty ratio measured by the measurement step from the table held by the holding unit, a counting step for counting the number of remaining prints in the print job, and the counting step A determination step for determining whether or not the remaining number of prints counted in step (b) is less than or equal to the remaining number of prints extracted in the extraction step, and the start timing is predicted when the determination step determines that the number is less than or equal to And a notification step for notifying to the prohibition step, wherein the prohibition step prohibits the control by the temperature control step and turns off the heating means when receiving a notification from the notification step. .
Here, the measurement step measures the immediately preceding duty ratio every time one sheet is printed, the extraction step extracts the remaining number of prints every time one sheet is printed, and the counting step includes one sheet print. It is also possible to count the number of remaining prints every time the printing is performed, and to determine the determination every time one sheet is printed.
Further, a pair of rotating bodies are arranged close to each other in a state where a fixing nip is formed between them, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at the pressurization and fixing temperature. A fixing temperature control method in an image forming apparatus for fixing a recording sheet to a recording sheet, wherein the image forming apparatus includes a heating unit that heats at least one of the pair of rotating bodies, and the control method includes the heating A detecting step for detecting the temperature of the rotating body heated by the means or a temperature corresponding to the temperature of the rotating body, and turning on and off the heating means based on the temperature detected by the detecting step during a print job. And a temperature control step for controlling the fixing temperature, and the fixing temperature when the print job is continued with the heating means virtually turned off. Assuming a transition period in which the lower limit temperature required for fixing is ensured until the end of the print job without turning on the heating means, and the fixing temperature is in the vicinity of the lower limit temperature at the end of the print job. A prediction step for predicting the start timing of the period, and a prohibition step for prohibiting the control by the temperature control step from the start timing predicted by the prediction step to the end of the print job and turning off the heating unit. And the prohibiting step restarts the control by the temperature control step when a temporary stop state is reached between the start timing and the end of the print job.
Further, a pair of rotating bodies are arranged close to each other in a state where a fixing nip is formed between them, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature to pass the toner image. A fixing temperature control method in an image forming apparatus for fixing a recording sheet to a recording sheet, wherein the image forming apparatus includes a heating unit that heats at least one of the pair of rotating bodies, and the control method includes the heating A detecting step for detecting the temperature of the rotating body heated by the means or a temperature corresponding to the temperature of the rotating body, and turning on and off the heating means based on the temperature detected by the detecting step during a print job. And a temperature control step for controlling the fixing temperature, and the fixing temperature when the print job is continued with the heating means virtually turned off. Considering a transition, it is assumed that a lower limit temperature necessary for fixing is ensured until the end of the print job without turning on the heating means, and the fixing temperature is close to the lower limit temperature at the end of the print job. A prediction step for predicting the start timing of the period, and a prohibition step for prohibiting control by the temperature control step and turning off the heating means from the start timing predicted by the prediction step to the end of the print job. And the prohibiting step restarts the control by the temperature control step when the number of prints increases between the start timing and the end of the print job.

[Embodiment 1]
<Overview>
In the first embodiment of the present invention, the timing to turn off the heater is predicted in consideration of the size of the recording sheet and the paper type, and after that timing, fixing is performed using the residual heat of the fixing material until the end of the print job. And an image forming apparatus that shifts to a power saving mode immediately after the end of the print job.

<Configuration>
FIG. 1 is a diagram illustrating an overall configuration of the image forming apparatus according to the first embodiment.
As shown in FIG. 1, the image forming apparatus 1 according to the first embodiment is a tandem color digital printer, and includes an image processing unit 3, a feeding unit 4, a fixing unit 5, and a control unit 6, and a network (for example, in-house) When a print execution instruction is received from an in-house terminal device, a color image is formed on a recording sheet and output in accordance with the instruction.

  The image processing section 3 is a part mainly responsible for image formation, and forms image toner images of yellow, magenta, cyan and black along with the intermediate transfer belt 11 circulating in the direction indicated by the arrow A. Units 3Y, 3M, 3C, and 3K are sequentially arranged, and an optical unit 10 including a light emitting element such as a laser diode is disposed below each image forming unit. In the image processing section 3, an image forming unit mainly composed of components having “Y” after the reference number generates an image of yellow toner, and similarly, “M” is added after the reference number. An image forming unit mainly composed of the constituent elements is a magenta toner image, and an image forming unit mainly composed of the constituent elements having “C” after the reference number is a cyan toner image. An image forming unit mainly composed of components having “K” after the reference number generates an image using black toner.

The image forming unit 3Y includes a photosensitive drum 31Y, and a charger 32Y, a developing device 33Y, a primary transfer roller 34Y, and a cleaner 35Y disposed around the photosensitive drum 31Y.
In generating an image using yellow toner, the charger 32Y uniformly charges the photosensitive drum 31Y, and the control unit 6 controls the laser beam L to the photosensitive drum 31Y uniformly charged by the optical unit 10. The electrostatic latent image is emitted to form an electrostatic latent image, and the developing device 33Y develops the formed electrostatic latent image with yellow toner, and the developed toner image is primarily transferred to the intermediate transfer belt 11 and primary transferred. Thereafter, the toner remaining on the photosensitive drum 31Y is removed by the cleaner 35Y.

The image forming units 3M, 3C, and 3K also have the same configuration as that of the image forming unit 3Y (the reference numerals are omitted in the drawing), and similarly generate images with toner of each color.
Each time the toner image primarily transferred to the intermediate transfer belt 11 passes through each of the image forming units, the respective colors are superimposed, and finally a full-color toner image is generated.
On the other hand, the feeding unit 4 is a part mainly responsible for transporting the recording sheet, and a paper feeding cassette 41 for storing the recording sheet S and a feeding roller 42 for feeding the stored recording sheet S one by one to the transporting path 43. And a timing roller pair 44 for timing to send out the fed recording sheet S and a secondary transfer roller 45, and the recording sheet S is conveyed to the secondary transfer position 46 and is generated on the intermediate transfer belt 11. The toner image is secondarily transferred to the recording sheet S at the secondary transfer position 46.

The fixing unit 5 is a belt-type fixing device, and heats and pressurizes the recording sheet S on which the toner image is secondarily transferred to fix the toner image on the recording sheet S. The fixing unit 5 will be described in detail below.
The recording sheet S after fixing is discharged to a discharge tray 72 by driving a discharge roller 71 and the like.
The control unit 6 is a controller that collectively controls the overall operation, temperature control, and the like of the image forming apparatus 1, and for each light-emitting element of the optical unit 10 for each image forming unit based on image data to be formed. A drive signal is generated, and the timing is adjusted so that the toner images of the respective colors are accurately superimposed in the primary transfer, or the toner images are accurately transferred to the recording sheet S in the secondary transfer.
(A) Details of Fixing Unit FIG. 2 is a diagram schematically illustrating the configuration of the fixing unit 5.

  As shown in FIG. 2, the fixing unit 5 has a pressure roller 54 disposed close to the fixing roller 52 via a fixing belt 53 that is wound around a heating roller 51 and a fixing roller 52 and is rotatably supported. Then, a fixing nip is formed at the contact portion between the fixing belt 53 and the pressure roller 54, the recording sheet on which the unfixed image is formed is passed through the fixing nip, and the unfixed image is heated on the recording sheet. Crimp.

  The heating roller 51 is configured by laminating a coating layer made of fluororesin or the like on the surface of a cylindrical steel or aluminum pipe to prevent wear with the fixing belt 53 (for example, an outer diameter of 25 mm, an aluminum hollow core). In a state where tension is applied to the fixing belt 53 together with the fixing roller 52, the fixing belt 53 is rotationally driven in accordance with the passing speed of the recording sheet.

  Further, a heater 55 (for example, a halogen lamp heater 990 W, a light emission length of 20 mm / 250 mm / 20 mm / total 290 mm, a heater light distribution of 115% / 100% / 115%) is inserted in the heating roller 51. The heating roller 51 is directly heated by the heat generated by the heater 55, the heat is conducted to the fixing belt 53, and the fixing belt 53 is heated to the fixing temperature.

The fixing roller 52 is configured by laminating an elastic layer such as silicone rubber or sponge on the surface of cylindrical steel or aluminum (for example, an outer diameter of 30 mm, iron solid core metal φ22 mm + rubber 4 mm + sponge 2 mm, nip) It is not heated directly by the heat generated by the heater 55 in the longitudinal direction (about 330 mm).
The fixing belt 53 is an endless belt configured by laminating an elastic layer such as silicone rubber and a coat layer made of fluorine resin or the like on the surface of a heat-resistant layer made of polyimide resin or nickel base material, and has flexibility. (For example, outer diameter 60 mm, nickel base material 45 μm + rubber 200 μm + PFA 30 μm, nip longitudinal direction about 320 mm).

The pressure roller 54 is configured by laminating an elastic layer such as silicone rubber and a release layer made of fluorine resin or the like on the surface of a cylindrical steel or aluminum pipe (for example, an outer diameter of 35 mm, an iron hollow core). Gold 2.5 mm + rubber 2.5 mm + PFA 30 μm, nip length direction about 330 mm).
Further, the fixing unit 5 in the illustrated example further includes a non-contact thermistor 56 (for example, disposed at two positions of 40 mm and 140 mm from the central sheet passing reference position), and the surface temperature of the fixing belt 53 near the heating roller 51 is adjusted. Output the corresponding voltage. Here, the non-contact thermistor 56 may be installed at a position where the temperature of the heating roller 51 is detected.
(B) Functional Configuration FIG. 3 is a diagram illustrating a functional configuration of the image forming apparatus 1 according to the first embodiment.

As illustrated in FIG. 3, the image forming apparatus 1 includes a heating unit 81, a fixing member 82, a temperature detection unit 83, an operation control unit 84, a temperature control unit 85, a prediction unit 86, and a prohibition unit 87.
The heating unit 81 corresponds to the heater 55 shown in FIG. 2 and is a heating source that heats the fixing member 82, and is turned on / off by the temperature control unit 85.
The fixing member 82 corresponds to the heating roller 51, the fixing roller 52, the fixing belt 53, and the pressure roller 54 shown in FIG. 2, and is heated by the heating unit 81, forms a fixing nip, and fixes the recording sheet. A rotating body that heats and pressurizes in the nip.

The temperature detector 83 corresponds to the non-contact thermistor 56 shown in FIG. 2 and detects the temperature of the fixing member 82.
The operation control unit 84 corresponds to a part of the function of the control unit 6 shown in FIG. 1 and controls the conveyance of the recording sheet, the operation of the fixing member 82, and the like.
The temperature control unit 85 corresponds to a part of the function of the control unit 6 shown in FIG. 1 and controls the fixing temperature by turning on and off the heating unit 81 based on the temperature detected by the temperature detection unit 83. .

  The prediction unit 86 corresponds to a part of the function of the control unit 6 shown in FIG. 1 and takes into account the transition of the fixing temperature when the print job is continued with the heating unit 81 virtually turned off. Assuming a period in which the lower limit temperature necessary for fixing is ensured until the end of the print job without turning on the heating unit 81, and the fixing temperature is close to the lower limit temperature at the end of the print job, Predict the start timing of the period.

FIG. 4 is a diagram illustrating a detailed functional configuration of the prediction unit 86.
As illustrated in FIG. 4, the prediction unit 86 includes a holding unit 861, an acquisition unit 862, an extraction unit 863, a count unit 864, a determination unit 865, and a notification unit 866.
The holding unit 861 holds a table that defines the number of remaining prints in the print job for each type of recording sheet as an index for predicting the start timing.

Here, the type of recording sheet indicates a combination of paper types such as thin paper, plain paper, thick paper, and OHP sheet, and paper sizes such as A5, B4, A4, B4, and A3.
Further, the remaining number of prints here is for predicting that it is the start timing when the number of recording sheets to be actually printed becomes smaller than this number of sheets, and forcibly turning off the heating unit 81. It is an indicator.

FIG. 5 is a diagram illustrating a table held in the holding unit 861.
The obtaining unit 862 obtains the type of recording sheet used for the remaining prints from the operation control unit 84.
The extraction unit 863 extracts the remaining number of prints corresponding to the type of the recording sheet acquired by the acquisition unit 862 from the table held in the holding unit 861.

For example, when the paper size “B4” and the paper type “thin paper” are obtained as the recording sheet type, “3.5” is extracted as the remaining number of prints from the table shown in FIG.
The counting unit 864 counts the number of remaining prints in the print job. In addition, when a plurality of print jobs are duplicated, the count unit 864 adds them together as a new print job, and during printing, interrupt printing, addition of a print job, and all or part of the print job are performed. If there is a change in the number of prints due to discarding or the like, the remaining number of prints is counted based on the number of prints after the change.

The determination unit 865 determines whether the remaining number of prints counted by the counting unit 864 is equal to or less than the number of remaining prints extracted by the extraction unit 863.
When the determination unit 865 determines that the following has occurred, the notification unit 866 predicts the start timing and notifies the prohibition unit 87 of the start timing.
For example, if the extracted remaining number of prints is “3.5”, the start timing is predicted when the remaining number of remaining prints reaches 3, and the prohibition unit 87 is notified. .

Upon receiving the notification from the notification unit 866, the prohibition unit 87 prohibits the temperature control by the temperature control unit 85 from the start timing predicted by the prediction unit 86 to the end of the print job, and turns off the heating unit 81. To the state.
In addition, the prohibition unit 87 resumes the temperature control by the temperature control unit 85 when the temporary stop state is reached between the start timing and the end of the print job or when the number of prints increases.

<Operation>
FIG. 6 is a diagram illustrating a temperature control procedure during fixing according to the first embodiment.
Hereinafter, a temperature control procedure during fixing will be described with reference to FIG.
(1) When the power is turned on, the operation control unit 84 waits until an instruction to start printing is received directly from the user or via a PC (personal computer) (step S1).

  (2) When an instruction to start a print job is received (step S1: YES), the operation control unit 84 determines the linear velocity of the fixing belt 53 according to the recording sheet material and finish designation (normal or high gloss, etc.). The linear velocity of the recording sheet and the target temperature in the temperature control are set, and the temperature controller 85 starts the temperature control (step S2). In the first embodiment, for example, when printing plain paper with normal settings, the linear velocity between the fixing belt 53 and the recording sheet is set to a linear velocity of 90 mm / s, the target temperature is set to 185 ° C., and for example, plain paper is used. Is set to print with high gloss, the linear velocity between the fixing belt 53 and the recording sheet is set to 45 mm / s, and the target temperature is set to 145 ° C.

(3) Wait until the temperature of the fixing member 82 reaches the target temperature (step S3).
(4) When the temperature of the fixing member 82 reaches the target temperature (step S3: YES), the warm-up is completed, and the temperature control unit 85 sets the temperature of the fixing member 82 within a predetermined range near the target temperature. Then, a print permission signal is issued and printing is started (step S4).
(5) When printing is started, the counting unit 864 counts the number of remaining prints in the print job (step S5). Here, if there is a change in the number of prints due to interrupt printing, addition of a print job, or discarding all or part of the print job, the remaining number of prints is counted based on the number of prints after the change.

  (6) The acquisition unit 862 acquires the type of recording sheet used for the remaining prints from the operation control unit 84, and the extraction unit 863 is acquired by the acquisition unit 862 from the table held in the holding unit 861. The remaining number of prints corresponding to the recording sheet type is extracted (step S6). If there are multiple types of recording sheets to be used for the remaining prints, extract the remaining number of prints for each type and select the smallest remaining number of prints from among them so as not to cause fixing failure. To do.

(7) The determination unit 865 determines whether or not the remaining number of prints counted in step S6 is equal to or less than the number of remaining prints extracted in step S3 (step S7). If it is not less than the remaining number of prints, the process returns to step S5.
(8) When the number of remaining prints is equal to or less (step S7: YES), the notification unit 866 predicts that it is the start timing, and notifies the prohibition unit 87 (step S8).

(9) Upon receiving the notification from the notification unit 866, the prohibition unit 87 prohibits the temperature control by the temperature control unit 85 and turns off the heating unit 81 (step S9).
(10) The prohibition unit 87 determines whether the print job has been temporarily stopped (step S10).
(11) When the temporary stop state is set (step S10: YES), the prohibition unit 87 restarts the temperature control by the temperature control unit 85 (step S11).

(12) Wait until the print job is resumed (step S12).
(13) When the print job is resumed (step S12: YES), the prohibition unit 87 prohibits the temperature control by the temperature control unit 85 and turns off the heating unit 81 (step S13).
(14) If the pause state is not established (step S10: NO, after step S12: YES), the prohibition unit 87 determines whether or not there is an increase in the number of prints due to interrupt printing or addition of a print job. Is determined (step S14).

(15) When there is an increase in the number of prints (step S14: YES), the prohibition unit 87 resumes the temperature control by the temperature control unit 85 (step S15).
(16) After waiting until the temperature of the fixing member 82 reaches the target temperature, the process returns to step S5 (step S16).
(17) If there is no increase in the number of prints (step S14: NO), the process waits until the print job is completed (step S17).

<Verification>
For comparison, FIG. 7A is detected by the temperature detection unit 83 when the heating unit 81 (here, the heater lamp) is turned off at the same time as the end of printing (A in the figure) for comparison. FIG. 7B is a diagram showing actual measurement results of actually measuring the temperature (here, the temperature of the fixing belt 53) and the power consumption. FIG. 7B shows the heating unit 81 turned off before the end of printing (D in the figure). FIG. 6 is a diagram showing an actual measurement result in the first embodiment in which the temperature detected by the temperature detection unit 83 and the power consumption are actually measured in the state (C in the figure).

In FIG. 7A, the temperature gradually begins to decrease from the end of printing (A in the figure), but since the printing has already been completed, it is difficult for heat to be taken away, so the temperature decreasing gradient is relatively gentle. Is hard to fall.
On the other hand, in FIG. 7B, the temperature gradually starts to decrease after the heater lamp is turned off (C in the figure), and the printing is not finished yet, so the recording sheet is deprived of heat and the temperature decreasing gradient is relatively steep. Yes, the temperature tends to drop. Further, until the end of printing (C to D in the figure), a lower limit temperature necessary for fixing (minimum fixing temperature of E in the figure) is secured, and when the printing is completed (D in the figure), the fixing temperature is the lower limit temperature. Since the temperature is in the vicinity, it can be said that the residual heat of the fixing material is effectively used.

Further, the actual measurement value of the power consumption when 10 sheets are printed in the control as shown in FIG. 7A is 22.96 WH, and the power consumption when 10 sheets are printed similarly in the control as shown in FIG. 7B. Since the predicted value of the amount is 19.63 WH, a power reduction effect of about 15% can be obtained.
<Summary>
As described above, according to the first embodiment, the heating unit can be turned off before the end of the print job at a different timing for each type of recording sheet. It is possible to eliminate errors due to the difference in the amount of heat generated, and to effectively control the fixing temperature by effectively utilizing the residual heat of the fixing material.

Therefore, power consumption can be suppressed.
[Modification 1]
<Overview>
In the first modification of the present invention, the duty ratio of the immediately preceding heater is measured to predict the timing to turn off the halogen heater, and after that timing, fixing is performed using the residual heat of the fixing material until the end of the print job. An image forming apparatus that shifts to a power saving mode immediately after the end of a print job.

<Configuration>
In the first modification, the prediction unit 86 in the first embodiment is replaced with a prediction unit 88, and other components and operations are the same as those in the first embodiment.
FIG. 8 is a diagram illustrating a detailed functional configuration of the prediction unit 88.
Similar to the prediction unit 86 of the first embodiment, the prediction unit 88 of the first modification corresponds to a part of the function of the control unit 6 illustrated in FIG. 1. As illustrated in FIG. A section 882, an extraction section 883, a count section 864, a determination section 865, and a notification section 866.

In addition, the same number is attached | subjected to the component provided with the function similar to Embodiment 1, and the description is abbreviate | omitted.
The measuring unit 881 measures the duty ratio of the heating unit 81.
Here, the duty ratio indicates a ratio at which the heating unit 81 is turned on within a certain period, and is represented by the sum of on time / (total of on time + total of off time).

In this modified example, every time one sheet is printed, the duty ratio required for the printing for the immediately preceding three sheets is measured.
The holding unit 882 holds a table that defines the number of remaining prints in the print job for each duty ratio as an index for predicting the start timing.
FIG. 9 is a diagram showing a table held in the holding unit 882.

The extraction unit 883 extracts the remaining number of prints corresponding to the duty ratio measured by the measurement unit 881 from the table held by the holding unit 882.
For example, when the duty ratio is “50%”, “3” is extracted from the table shown in FIG.
<Operation>
FIG. 10 is a diagram showing a temperature control procedure at the time of fixing in the first modification.

The temperature control procedure during fixing will be described below with reference to FIG.
In addition, the same number is attached | subjected to the step which performs the process similar to the procedure of FIG. 6 in Embodiment 1, and the description is abbreviate | omitted.
(1) to (5) Processing similar to (1) to (5) in FIG. 6 in the first embodiment is performed (steps S1 to S5).

(6) The measuring unit 881 measures the duty ratio of the heating unit 81 (step S21).
(7) The extraction unit 883 extracts the remaining number of prints corresponding to the duty ratio measured by the measurement unit 881 from the table held by the holding unit 882 (step S22).
(8) The determination unit 865 determines whether or not the remaining number of prints counted in step S6 is equal to or less than the number of remaining prints extracted in step S22 (step S23). If it is not less than the remaining number of prints, the process returns to step S5.

(9) When the number of remaining prints is less than or equal to the number of remaining prints (step S23: YES), the notification unit 866 predicts that it is the start timing and notifies the prohibition unit 87 (step S24).
(10)-(18) Processing similar to (9)-(17) of FIG. 6 in the first embodiment is performed (steps S9-S17).
<Summary>
As described above, according to the first modification, the heating unit can be turned off before the end of the print job at different timings depending on the duty ratio. It is possible to eliminate an error caused by a difference in the amount of heat taken due to a difference in recording sheet or a change in the environment, and to effectively control the fixing temperature by effectively using the residual heat of the fixing material.

Therefore, power consumption can be suppressed.
Note that a program that allows a computer to execute the operations of the first embodiment and the first modification is recorded on a computer-readable recording medium, and this recording medium can be distributed and traded. In addition, the program may be distributed through a network or the like, for example, and may be traded, or may be displayed on a display device, printed, and presented to a user.

  Here, the computer-readable recording medium is, for example, a removable recording medium such as a floppy (registered trademark) disk, CD, MO, DVD, or memory card, and a fixed recording medium such as a hard disk or semiconductor memory. There is no particular limitation.

The present invention can be widely applied to the technical field of image forming apparatuses including a fixing device.
According to the present invention, the remaining heat of the fixing material can be effectively used and the fixing temperature can be appropriately controlled, so that power consumption can be suppressed and its industrial utility value is extremely high.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to Embodiment 1. FIG. FIG. 3 is a diagram schematically illustrating a configuration of a fixing unit 5. 2 is a diagram illustrating a functional configuration of an image forming apparatus 1 according to Embodiment 1. FIG. It is a figure which shows the detailed function structure of the estimation part 86. FIG. 6 is a diagram showing a table held in a holding unit 861. FIG. FIG. 3 is a diagram illustrating a temperature control procedure during fixing in the first embodiment. (A) is an actual measurement in which, for comparison, the temperature detected by the temperature detection unit 83 and the power consumption were actually measured when the heating unit 81 was turned off at the end of printing as in the prior art. It is a figure which shows a result, (b) is the implementation which actually measured the temperature detected by the temperature detection part 83, and power consumption when the heating part 81 was made into the OFF state before completion | finish of printing. It is a figure which shows the measurement result in the form 1. It is a figure which shows the detailed functional structure of the estimation part 88. FIG. FIG. 10 shows a table held in a holding unit 882. FIG. 10 is a diagram illustrating a temperature control procedure at the time of fixing in Modification 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Image process part 4 Feeding part 5 Fixing part 6 Control part 10 Optical part 11 Intermediate transfer belt 3Y, 3M, 3C, 3K Image forming unit 31Y, 31M, 31C, 31K Photosensitive drum 32Y, 32M, 32C , 32K Charger 33Y, 33M, 33C, 33K Developer 34Y, 34M, 34C, 34K Primary transfer roller 35Y, 35M, 35C, 35K Cleaner 41 Paper feed cassette 42 Feeding roller 43 Conveyance path 44 Timing roller pair 45 Secondary transfer Roller 46 Secondary transfer position 51 Heating roller 52 Fixing roller 53 Fixing belt 54 Pressure roller 55 Heater 56 Non-contact thermistor 71 Paper discharge roller 72 Paper discharge tray 81 Heating part 82 Fixing member 83 Temperature detection part 84 Operation control part 85 Temperature control Part 86 Prediction part 87 Prohibition part 88 Prediction Part 861 holding section 862 acquiring unit 863 extracting unit 864 counting unit 865 determination unit 866 notifying unit 881 measuring unit 882 holder 883 extractor

Claims (12)

A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet,
Heating means for heating at least one of the pair of rotating bodies;
Detecting means for detecting the temperature of the rotating body heated by the heating means, or a temperature corresponding to the temperature of the rotating body;
A temperature control means for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection means during a print job;
Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means Predicting means for assuming a period in which the fixing temperature becomes a temperature in the vicinity of the lower limit temperature at the end of the print job and predicting the start timing of the period,
Prohibiting means for prohibiting the control by the temperature control means and turning off the heating means from the start timing predicted by the prediction means to the end of the print job;
With
The prediction means includes
As an index for predicting the start timing, a holding unit that holds a table that defines the number of remaining prints in a print job for each type of recording sheet;
Means for obtaining the type of recording sheet;
Extracting means for extracting the remaining number of prints corresponding to the type of the recording sheet obtained by the obtaining means from the table held by the holding means;
Counting means for counting the number of remaining prints in the print job;
Determining means for determining whether or not the number of remaining prints counted by the counting means is equal to or less than the number of remaining prints extracted by the extracting means;
A notification means for predicting the start timing and notifying to the prohibition means when it is determined by the determination means that:
The prohibition means is
Wherein when the notification unit notified, the prohibited controlled by the temperature control means, said heating means images forming device you characterized in that the state of off. The table held by the holding means is
The image forming apparatus according to claim 1 , wherein the number of remaining prints is defined for each paper type and sheet size of the recording sheet. A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet,
Heating means for heating at least one of the pair of rotating bodies;
Detecting means for detecting the temperature of the rotating body heated by the heating means, or a temperature corresponding to the temperature of the rotating body;
A temperature control means for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection means during a print job;
Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means Predicting means for assuming a period in which the fixing temperature becomes a temperature in the vicinity of the lower limit temperature at the end of the print job and predicting the start timing of the period,
Prohibiting means for prohibiting the control by the temperature control means and turning off the heating means from the start timing predicted by the prediction means to the end of the print job;
With
The prediction means includes
Measuring means for measuring a duty ratio of the heating means;
As an index for predicting the start timing, holding means for holding a table that defines the number of remaining prints in a print job for each duty ratio;
Extracting means for extracting the remaining number of prints corresponding to the duty ratio measured by the measuring means from the table held by the holding means;
Counting means for counting the number of remaining prints in the print job;
Determining means for determining whether or not the number of remaining prints counted by the counting means is equal to or less than the number of remaining prints extracted by the extracting means;
A notification means for predicting the start timing and notifying to the prohibition means when it is determined by the determination means that:
The prohibition means is
Wherein when the notification unit notified, the prohibited controlled by the temperature control means, said heating means images forming device you characterized in that the state of off. The measuring means includes
Every time you print one sheet, measure the previous duty ratio,
The extraction means includes
For each print, extract the remaining number of prints,
The counting means includes
Every time one sheet is printed, the remaining number of prints is counted ,
The determination means includes
The image forming apparatus according to claim 3 , wherein a determination is made every time one sheet is printed. A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet,
Heating means for heating at least one of the pair of rotating bodies;
Detecting means for detecting the temperature of the rotating body heated by the heating means, or a temperature corresponding to the temperature of the rotating body;
A temperature control means for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection means during a print job;
Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means Predicting means for assuming a period in which the fixing temperature becomes a temperature in the vicinity of the lower limit temperature at the end of the print job and predicting the start timing of the period,
Prohibiting means for prohibiting the control by the temperature control means and turning off the heating means from the start timing predicted by the prediction means to the end of the print job;
With
The prohibition means is
Wherein the start timing until the end of the print job, if it becomes paused, images forming device you characterized by resuming the control by the temperature control means. A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. An image forming apparatus for fixing a toner image to a recording sheet,
Heating means for heating at least one of the pair of rotating bodies;
Detecting means for detecting the temperature of the rotating body heated by the heating means, or a temperature corresponding to the temperature of the rotating body;
A temperature control means for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection means during a print job;
Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means Predicting means for assuming a period in which the fixing temperature becomes a temperature in the vicinity of the lower limit temperature at the end of the print job and predicting the start timing of the period,
Prohibiting means for prohibiting the control by the temperature control means and turning off the heating means from the start timing predicted by the prediction means to the end of the print job;
With
The prohibition means is
Wherein the start timing until the end of the print job, if the number of prints is increased, images forming device you characterized by resuming the control by the temperature control means. A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. A fixing temperature control method in an image forming apparatus for fixing a toner image on a recording sheet,
The image forming apparatus includes:
Heating means for heating at least one of the pair of rotating bodies;
The control method is:
A detection step of detecting the temperature of the rotating body heated by the heating means or a temperature corresponding to the temperature of the rotating body;
A temperature control step for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection step during a print job;
Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means And a prediction step for predicting the start timing of the period assuming a period in which the fixing temperature is a temperature in the vicinity of the lower limit temperature at the end of the print job.
Wherein the start timing which is predicted by the prediction step, until the end of the print job, and prohibits the control by the temperature control step, viewed contains a prohibition step of the state of turning off the heating means,
The image forming apparatus further includes:
As an index for predicting the start timing, a holding unit that holds a table that defines the number of remaining prints in a print job for each type of recording sheet,
The prediction step includes
An obtaining step for obtaining the type of the recording sheet;
An extraction step for extracting the remaining number of prints corresponding to the type of the recording sheet obtained in the obtaining step from the table held in the holding unit;
A counting step for counting the number of remaining prints in the print job;
A determination step of determining whether or not the number of remaining prints counted in the counting step is equal to or less than the number of remaining prints extracted in the extraction step;
A notification step of predicting that it is the start timing and notifying to the prohibition step when it is determined by the determination step that:
The prohibition step includes:
When the notification is received from the notification step, the control by the temperature control step is prohibited, and the heating unit is turned off .   The table held by the holding means is
  The number of remaining prints must be specified for each recording sheet type and sheet size.
  The method of controlling a fixing temperature according to claim 7.   A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. A fixing temperature control method in an image forming apparatus for fixing a toner image on a recording sheet,
  The image forming apparatus includes:
  Heating means for heating at least one of the pair of rotating bodies;
  The control method is:
  A detection step of detecting the temperature of the rotating body heated by the heating means or a temperature corresponding to the temperature of the rotating body;
  A temperature control step for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection step during a print job;
  Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means And a prediction step for predicting the start timing of the period assuming a period in which the fixing temperature is a temperature in the vicinity of the lower limit temperature at the end of the print job.
  A prohibition step of prohibiting control by the temperature control step and turning off the heating means from the start timing predicted by the prediction step to the end of the print job;
  Including
  The image forming apparatus further includes:
  As an index for predicting the start timing, a holding unit that holds a table that defines the number of remaining prints in a print job for each duty ratio,
  The prediction step includes
  A measuring step for measuring a duty ratio of the heating means;
  An extraction step for extracting the remaining number of prints corresponding to the duty ratio measured by the measurement step from the table held by the holding unit;
  A counting step for counting the number of remaining prints in the print job;
  A determination step of determining whether or not the number of remaining prints counted in the counting step is equal to or less than the number of remaining prints extracted in the extraction step;
  A notification step of predicting that it is the start timing and notifying to the prohibition step when it is determined by the determination step that:
  The prohibition step includes:
  Upon receiving notification from the notification step, the control by the temperature control step is prohibited and the heating means is turned off.
  And a fixing temperature control method.   The measuring step includes
  Every time you print one sheet, measure the previous duty ratio,
  The extraction step includes
  For each print, extract the remaining number of prints,
  The counting step includes
  Every time one sheet is printed, the remaining number of prints is counted,
  The determination step includes
  Judge every time you print one sheet
  The fixing temperature control method according to claim 9.   A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. A fixing temperature control method in an image forming apparatus for fixing a toner image on a recording sheet,
  The image forming apparatus includes:
  Heating means for heating at least one of the pair of rotating bodies;
  The control method is:
  A detection step of detecting the temperature of the rotating body heated by the heating means or a temperature corresponding to the temperature of the rotating body;
  A temperature control step for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection step during a print job;
  Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means And a prediction step for predicting the start timing of the period assuming a period in which the fixing temperature is a temperature in the vicinity of the lower limit temperature at the end of the print job.
  A prohibition step of prohibiting control by the temperature control step and turning off the heating means from the start timing predicted by the prediction step to the end of the print job;
  Including
  The prohibition step includes:
  When the print job is temporarily stopped from the start timing to the end of the print job, the control by the temperature control step is resumed.
  And a fixing temperature control method.   A pair of rotating members are arranged close to each other with a fixing nip formed therebetween, and a recording sheet on which an unfixed toner image is formed is passed through the fixing nip while being heated at a pressure and a fixing temperature. A fixing temperature control method in an image forming apparatus for fixing a toner image on a recording sheet,
  The image forming apparatus includes:
  Heating means for heating at least one of the pair of rotating bodies;
  The control method is:
  A detection step of detecting the temperature of the rotating body heated by the heating means or a temperature corresponding to the temperature of the rotating body;
  A temperature control step for controlling the fixing temperature by turning the heating means on and off based on the temperature detected by the detection step during a print job;
  Considering the transition of the fixing temperature when the print job is continued with the heating means virtually turned off, the lower limit temperature necessary for fixing until the end of the print job without turning on the heating means And a prediction step for predicting the start timing of the period assuming a period in which the fixing temperature is a temperature in the vicinity of the lower limit temperature at the end of the print job.
  A prohibition step of prohibiting control by the temperature control step and turning off the heating means from the start timing predicted by the prediction step to the end of the print job;
  Including
  The prohibition step includes:
  When the number of prints increases between the start timing and the end of the print job, the control by the temperature control step is resumed.
  And a fixing temperature control method.

Images