JP5136113B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a fixing unit that thermally fixes an image formed on a sheet, and more particularly to a technique for reducing power consumption in the fixing unit.

  For example, Patent Document 1 discloses a technique for reducing power consumption in a fixing unit as described below. That is, when the power is turned on, first, an expected time X required for executing an operation (warm-up) for raising the temperature of the fixing unit to a temperature required for heat fixing (target temperature) is calculated. Start page expansion of the print data of the job. Then, while performing page expansion, the expected time (remaining page expansion time) A required until the end of page expansion is calculated every moment, and when the remaining page expansion time A coincides with time X, power is supplied to the heater of the fixing unit. And start warming up. Warm-up and page development are almost finished at the same time, and printing is started when both are finished.

By matching the end timings of both the warm-up and page expansion of the fixing unit, for example, the warm-up has ended first. Thus, it is unnecessary to keep the temperature of the fixing unit at the target temperature, and power consumption in the fixing unit can be reduced accordingly.
JP 2006-251363 A

  In Patent Document 1, only page expansion is disclosed as an operation in parallel with the warm-up of the fixing unit. However, in recent years, for example, due to the high quality of reproduced images and the diversification of peripheral devices such as scanners and sorters, for example, (a) each color toner pattern is formed on a photosensitive drum or an intermediate transfer belt. Each color toner pattern is detected, and image stabilization such as registration correction for correcting the deviation in image forming timing of each color and density correction for correcting the image density of each color from the detection result, (b) the optical unit of the scanner and the sorter An initial operation for operating a bin or the like to return to the home position is also performed in parallel. Hereinafter, operations other than warm-up of the fixing unit, such as page development, image stabilization, and initial operation, and operations required before image formation are collectively referred to as “initial operations”.

  In the initial operation, the photosensitive drum, the optical unit, and the like are driven by a motor, or a high voltage is output from a high-voltage transformer to a charger or a developer for forming a toner pattern. Looking at the initial operation over time, there are sections where power consumption is low, such as only the motor being driven, but there are sections where power consumption increases due to overlapping operations such as motor driving and charging, Even if it does not reach the heater of the fixing unit, a certain amount of power is consumed.

  As the power required for the initial operation is increasing in this way, if you try to use a heater with the same rated power consumption in the same way as before, the commercial power supply will be in the middle of performing the initial operation and warm-up in parallel. May exceed the rating, for example, 15 [A]. In order to avoid this, the heater can be replaced with one that consumes less power, but the amount of heat generated per unit time decreases, and it takes time to raise the temperature and the time required to warm up becomes longer.

  The present invention has been made in view of the above-mentioned problems, and aims to suppress power consumption of the fixing unit by performing initial operation and warming up of the fixing unit in parallel without exceeding the rating of the power source. An object of the present invention is to provide an image forming apparatus capable of performing the above.

In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus that forms an image on a sheet and thermally fixes the formed image to the sheet using a fixing member of a fixing unit. A heater that heats the fixing member and varies a calorific value in accordance with a magnitude of power supplied; a detecting unit that detects a temperature of the fixing member; and power supplied to the heater to control the fixing member. Power supply control means for performing warm-up to raise the temperature from the temperature detected by the detection means to a target temperature necessary for heat fixing, and initial operation required before starting the image formation, excluding power supplied to the heater comprising obtaining means for obtaining a time course of would require the to run the power supply value, wherein the power supply control unit performs in parallel the initial operation and the warm-up, and the initial operation and War Setting means for setting a constant power value to be required as the power supplied to the heater in order to match the end times of both up, and the power that will be required for the execution of the initial operation If a certain power supply is performed in parallel, and there is a section where the sum is expected to exceed a predetermined upper limit value, the value of the constant power is lowered for the section, which corresponds to the reduced amount. Correction means for compensating the amount of electric power by increasing the value of the constant power in other sections other than the section, and correcting the value of the constant power so that the sum is less than or equal to the upper limit value. The time transition of the corrected power is determined as the power supplied to the heater .

  In addition, the setting means may end the initial operation and the warm-up as long as a certain amount of electric power is continuously supplied to the heater with respect to the time required for the initial operation and the temperature detected by the detection unit. A constant power value to the heater is set with reference to information indicating whether or not can be matched.

  Further, the setting means is required as power supplied to the heater in order to match the end times of both the initial operation and the warm-up for the remaining period until the end of the initial operation during the execution of the initial operation. When the resetting is performed, the correction unit resets the value of the constant power that is to be set and the time period of the initial operation for the remaining period. The reset power value is corrected so that the sum of the power value and the power value that will be required for execution is less than or equal to the upper limit value.

  Furthermore, the correction means compensates by averaging and allocating the amount of power corresponding to the lowered amount to the other section.

  The correction means compensates by allocating the amount of power corresponding to the reduced amount to the other section, and the ratio of the allocation amount is the first unit section of the first section of the first section. It is characterized by being larger than the second unit interval that is later in time than the unit interval.

  In addition, the power supply control means includes a measurement unit that measures the power that is currently consumed by the device, and the power supply control unit includes a power supply value that is required to execute the initial operation and a power supply value to the determined heater. When the measured value by the measuring means during execution of the initial operation and warm-up is larger than the calculated total value, the difference between the measured value and the total value is calculated. A value obtained by subtracting the corresponding amount from the predetermined upper limit value is set as a new upper limit value, and the time of the power supply value to the heater is set for the remaining time of the initial operation using the set new upper limit value. The transition is reset, and the power supplied to the heater is controlled according to the time transition of the reset power supply value.

  By determining the power supply to the heater in this way, it is possible to suppress the power consumption of the fixing unit by performing the initial operation and the warm-up in parallel without exceeding the power supply rating as a predetermined upper limit, for example. Become.

  Hereinafter, an example in which an embodiment of an image forming apparatus according to the present invention is applied to a tandem color digital copying machine (hereinafter simply referred to as “copying machine”) will be described.

  FIG. 1 is a diagram showing the overall configuration of the copying machine 1.

  As shown in FIG. 1, the copying machine 1 is roughly divided into an automatic document feeder 11 that automatically feeds a document, an image reader unit 12 that reads an image of the conveyed document, and an image read by the image reader unit 12. Are printed on a recording sheet and reproduced, and a finisher 14 for accommodating the printed sheet.

  The automatic document feeder 11 conveys the document placed on the document placement tray 15 to a predetermined reading position on the platen glass 16, and when the document is scanned by the scanner 21 of the image reader unit 12, the document is discharged. It is a known one that is discharged onto the paper tray 17.

  The image reader unit 12 includes a scanner 21 and a drive motor 22. The scanner 21 includes an exposure lamp that irradiates a document, a lens that condenses the reflected light, a full-color CCD sensor that converts the collected light into an electrical signal, and the like. The rotation axis of the drive motor 22 is connected to the scanner 21 via a wire or the like, and moves the scanner 21 in the arrow B direction or the opposite direction.

  When the document is conveyed from the automatic document feeder 11 to the reading position on the platen glass 16, the scanner 21 is moved in the direction of arrow B to expose the document on the platen glass 16. The image of the document is photoelectrically converted by the CCD sensor to become red (R), green (G), and blue (B) component electrical signals, which are sent to the control unit 60. When the exposure of one original is completed, the scanner 21 is returned to the position (home position) in FIG. In the present embodiment, a position detection sensor 23 for detecting that the scanner 21 is located at the home position (starting origin position) is arranged, and when the exposure of the document is completed, the scanner 21 is moved to the home position. A process of moving the scanner 21 in the direction opposite to the arrow B is detected until it is detected that the position is located.

  The printer unit 13 forms an image by a known electrophotographic method, and includes an image processing unit 30, a feeding unit 40, a fixing unit 50, and the like.

  The image processing unit 10 includes image forming units 31Y, 31M, 31C, and 31K corresponding to Y to K colors, an intermediate transfer belt 32, and the like.

  The image forming unit 31 </ b> Y includes the photosensitive drum 3 and a charger 4, an exposure unit 5, a developing unit 6, a primary transfer roller 7, and a cleaner for cleaning the photosensitive drum 3 disposed around the photosensitive drum 3. A Y-color toner image is formed on the photosensitive drum 3. The other image forming units 31M to 31K have basically the same configuration as the image forming unit 31Y, and create toner images of corresponding colors. In the figure, the reference numerals are omitted.

  The intermediate transfer belt 32 is an endless belt, is stretched around a driving roller 33, a driven roller 34, and a tension roller 35 and runs around in the direction of arrow A.

  The feeding unit 40 includes a sheet feeding cassette 41 on which the sheet S is set, a feeding roller 42, a conveying roller pair 43, a timing roller pair 44, and a driving roller that sandwiches the intermediate transfer belt 32 at the secondary transfer position 47. And a secondary transfer roller 45 disposed opposite to the main body 33.

  The feeding roller 42 feeds the sheets S set in the paper feed cassette 41 one by one to the conveyance path 49.

  The conveyance roller pair 43 conveys the sheet S fed to the conveyance path 49 to the timing roller pair 44, and the timing roller pair 44 takes a timing to send the conveyed sheet S to the secondary transfer position 47.

  The fixing unit 50 is based on an electromagnetic induction heating method, and includes a fixing roller 51, a pressure roller 52, an electromagnetic induction coil 53, a temperature detection sensor 54, an inverter circuit 55, and the like.

  The fixing roller 51 as a fixing member has an electromagnetic induction heat generating layer and a heat-resistant release layer formed by coating with a fluororesin on the surface.

  The pressure roller 52 has a releasable heat-resistant rubber layer formed on the surface thereof, and is pressed against the fixing roller 51. By this pressure contact, a fixing nip is secured between the fixing roller 51 and the pressure roller 52. The fixing roller 51 receives a rotational driving force from a driving source (not shown) and rotates in the direction of the arrow in the figure, and the pressure roller 52 rotates following the rotation of the fixing roller 51.

  The electromagnetic induction coil 53 as a heater is disposed along the outer peripheral surface of the fixing roller 51 so as to cover approximately half of the circumference of the fixing roller 51, and receives a supply of AC power from the inverter circuit 55 to generate a high-frequency magnetic field. The electromagnetic induction heat generating layer of the fixing roller 51 is caused to generate heat. Since the principle of heat generation by electromagnetic induction is known, the description thereof is omitted here. Hereinafter, the electromagnetic induction coil is referred to as a heater.

  The inverter circuit 55 can change the magnitude of the output power, and supplies the heater 53 with AC power having a magnitude indicated by the control unit 60. Here, the amount of heat generated by electromagnetic induction from the heater 53 increases as the output power increases.

  The temperature detection sensor 54 is a known sensor that detects the surface temperature of the fixing roller 51. The rotating members such as the photosensitive drum 3, the intermediate transfer belt 32, the feeding roller 42, and the pressure roller 52 disposed in the printer unit 13 are driven by the driving force of the driving motor 38.

  When the control unit 60 receives the image data of each color component of red (R), green (G), and blue (B) of the document image read by the CCD sensor of the image reader unit 12, the control unit 60 performs processing such as known correction. Then, the data is converted into data of each reproduction color of yellow (Y), magenta (M), cyan (C), and black (K), and temporarily stored in the image memory 104 (FIG. 2). Then, the converted data is read out for each scanning line in synchronization with the feeding of the sheet S, and a drive signal for the laser diode arranged in the exposure unit 5 of the image forming units 31Y to 31K is generated. Drive. Thereby, the photosensitive drum 3 is exposed and scanned by the laser beam from the exposure unit 5 for each of the image forming units 31Y to 31K.

  Before receiving this exposure scanning, the photosensitive drum 3 is uniformly charged by the charger 4 for each of the image forming units 31Y to 31K, and should be formed on the photosensitive drum 3 by laser light exposure. An electrostatic latent image of the image is formed, and the formed electrostatic latent image is developed with toner by the developing device 6.

  The toner images of the respective colors are primarily transferred onto the intermediate transfer belt 32 under the action of electrostatic force due to the electric field generated between the primary transfer roller 7 and the photosensitive drum 3. At this time, the image forming operations for the respective colors are executed at different timings so that the toner images are superimposed and transferred at the same position on the intermediate transfer belt 32. Each color toner image superimposed on the intermediate transfer belt 32 moves to the secondary transfer position 47 as the intermediate transfer belt 32 rotates.

  The sheet S is fed through the timing roller pair 44 in the feeding unit 40 in accordance with the timing of the image forming operation, and the sheet S is connected to the intermediate transfer belt 32 at the secondary transfer position 47. The toner image on the intermediate transfer belt 32 is transferred to the sheet S in a lump under the action of an electrostatic force generated by the electric field generated between the secondary transfer roller 45 and the drive roller 33. Next transferred.

  The sheet S that has passed the secondary transfer position 47 is conveyed to the fixing unit 50, and when the toner image is fixed to the sheet S by heating and pressurization when passing through the fixing unit 50, the sheet S is passed through the conveying roller pair 48. It is sent to the horizontal transport unit 61, transported by transport roller pairs 62 and 63 in the horizontal transport unit 61, and sent to the finisher 14.

  The finisher 14 includes storage bins 71 and 72 that store the sheet S, conveyance roller pairs 73 to 76 that convey the sheet S, a switching claw 77, a drive motor 78, and the like.

  The storage bin 71 is fixed to a finisher main body frame (not shown), and can store several tens of sheets S. The storage bin 72 is supported so as to be movable between a solid line position (home position) and a broken line position (lower limit position) in the figure, and the drive motor 78 increases as the number of sheets S stored increases. Is controlled so as to gradually move downward from the home position to the lower limit position under the driving force, and the maximum amount of sheets S (for example, about 1000 sheets) corresponding to the movement stroke from the home position to the lower limit position is loaded. It can be accommodated.

  The switching claw 77 is for switching the conveyance path of the sheet S to 81 or 82, and is switched to either the solid line position or the broken line position in the figure by an actuator (not shown). In the present embodiment, a user can select a storage bin by a key operation or the like before executing a copy job on an operation panel 90 (broken line) arranged on the front surface of the apparatus, and a sheet S is placed in the selected storage bin. The conveyance path is switched by the switching claw 77 so as to be accommodated.

  Further, a position detection sensor 79 for detecting that the storage bin 72 is located at the home position (upper limit position), and presence / absence of a sheet for detecting that the sheet bundle stored in the storage bin 72 has been removed. When a detection sensor (not shown) is provided and removal of the sheet bundle is detected, a process of moving the storage bin 72 upward is detected until it is detected that the storage bin 72 is located at the home position. .

  FIG. 2 is a diagram illustrating a configuration of the control unit 60.

  As shown in the figure, the control unit 60 includes a CPU 101, a ROM 102, a RAM 103, an image memory 104, a timer 105, a fixing target temperature storage unit 106, an initial operation information storage unit 107, and a power upper limit information storage unit as main components. 108, a heater supply reference power value information storage unit 109 is provided, and these are communicably connected via a bus 111.

  The CPU 101 reads out a program necessary for control from the ROM 102 and controls the operations of the automatic document feeder 11, the image reader unit 12, the printer unit 13, and the finisher 14 to execute a smooth copy operation. When the main switch of the apparatus is turned on (when the power is turned on), the initial operation and the warm-up of the fixing unit 50 are performed in parallel.

  As the initial operation, for example, there are an initial operation of each of the scanner and the finisher and an image stabilization operation of the printer unit 13.

  The initial operation of the scanner 21 is for checking the operation of the scanner 21 and preparing for scanning. Regardless of whether or not the scanner 21 is at the home position, the scanner 21 is moved by a predetermined distance. Return to the home position and stop. The initial operation of the finisher 14 is for checking the operation of the storage bin 72 and preparing for sheet storage. The storage bin 72 is temporarily moved regardless of whether or not the storage bin 72 is at the home position. After moving it downward by a predetermined distance, it returns to the home position and stops.

  The image stabilization operation includes registration correction and density correction. In the resist correction, a predetermined Y to K color toner pattern is formed on the intermediate transfer belt 32, and the formed Y to K color toner pattern is detected by the sensor 39 (FIG. 1). Thus, the pattern interval between different colors is calculated, and the deviation of the exposure timing of each color is corrected from the calculation result.

  In the density correction, a toner pattern having a plurality of gradations different for each color, different from the resist correction, is formed on the intermediate transfer belt 32, the density of each toner pattern is detected by the sensor 39, and the detection result is used. The image density of each color is corrected.

  The warm-up of the fixing unit 50 (hereinafter abbreviated as “warm-up”) supplies power to the heater 53 to change the surface temperature of the fixing roller 51 from the current temperature to a temperature (target temperature) required for fixing, for example, In this operation, the temperature is raised to 190 [° C.]. In the present embodiment, a heater power value setting process (described later) for setting a power value to be supplied to the heater 53 before the warm-up is started so that the warm-up end timing coincides with the initial operation end timing. Then, after setting the power value, the inverter circuit 55 is instructed to supply the set power value to the heater 53, thereby executing warm-up.

  Further, the CPU 101 receives a detection signal from the temperature detection sensor 54 during standby (ready state) or during execution of a copy job, monitors the surface temperature of the fixing roller 51, and sets the surface temperature of the fixing roller 51 as a target. The inverter circuit 55 is instructed to control the amount of power supplied to the heater 53 so that the temperature is maintained.

  The RAM 103 serves as a work area for the CPU 101.

  The fixing target temperature storage unit 106 stores information indicating the target temperature of the fixing unit 50.

  The initial operation information storage unit 107 stores information (initial operation information) indicating an operation item to be executed as an initial operation and a time transition of electric power required to execute each operation item.

  FIG. 3 is a diagram illustrating an example of the contents of the initial operation information.

  As shown in the figure, the initial operation information is information in which an initial operation elapsed time is associated with an initial operation item and necessary power. The initial operation includes scanner, finisher, stabilization 1, stabilization 2, and other execution items. Here, the scanner and the finisher correspond to the initial operations of the scanner and the finisher. Stabilization 1 corresponds to the above-described resist correction, and stabilization 2 corresponds to density correction. The other is an operation of supplying electric power to a member that needs to be energized, such as the operation panel 90.

  In the initial operation, the execution order and the power assumed to be necessary are determined in advance. For example, the initial operation of the scanner starts 3 seconds after the start of the initial operation and is executed for 5 seconds, and it is necessary to continuously supply power of 200 [W], and the initial operation of the finisher is 4 of the initial operation start. Starting from 2 seconds later, a part of the time zone is executed for 8 seconds while overlapping with the initial operation of the scanner.

  This figure shows an example in which the total time (initial operation total time) P required for execution of the initial operation is 28 seconds, and is required for execution of the initial operation every unit time (1 second). The expected power (the sum of the power in each execution item) is shown as the system power Ws. For example, 600 [W] is required for 1 second from 5 seconds to 6 seconds. Note that the power to be supplied to the heater 53 for warm-up is excluded from the power for the initial operation.

  4 is a timing chart rewritten to make it easy to understand the time transition of the power supply in FIG. 3, FIG. 4 (a) shows the execution power, and FIG. 4 (b) shows the system power Ws. ing. In addition, although the example which performs both stabilization 1 and 2 was demonstrated as image stabilization operation | movement, you may perform so that either one may be switched alternately, for example, whenever a power supply is turned ON. For example, when only the stabilization 1 is executed, the operation of the stabilization 2 is not necessary, and the entire initial operation time P is 16 seconds. In this configuration, as the initial operation information, for example, information for executing only stabilization 1 and other information for executing only stabilization 2 are stored and read alternately. be able to.

  Returning to FIG. 2, the power upper limit information storage unit 108 stores information indicating the rating of the external commercial power supply 19, for example, 1500 [W] (power use upper limit information). The value indicated in this information is the upper limit value of power that can be used by the apparatus.

  The heater supply reference power value information storage unit 109 stores heater supply reference power value information. FIG. 5 is a diagram illustrating an example of the content of the heater supply reference power value information.

  As shown in the figure, the heater supply reference power value information is obtained when the surface temperature of the fixing roller 51 at the start of warm-up is T [° C.] and the time required to execute the initial operation is P [seconds]. This is information indicating how much constant power [W] is supplied so that the end timings of both can be matched when the initial operation and the warm-up are performed in parallel. Specifically, for example, when T = 30 [° C.] and P = 28 [seconds], a constant power of 1150 [W] is supplied to the reference power value Wb for 28 seconds from the start to the end of the initial operation. If the supply is continued, the surface temperature of the fixing roller 51 should reach the target temperature at the end of the initial operation. In this sense, the reference power value Wb can be said to be a power supply value that should be required as a constant supply power to the heater 53 in order to make the initial operation coincide with the end of warm-up.

  The reference power value Wb is obtained in advance from an experiment or the like in consideration of the configuration of the fixing unit 50, mainly the heat capacity of members such as the fixing roller 51, the amount of heat generated by the heater 53, the relationship between the temperature T and the time P, and the like. The information is not limited to the information in the table format as described above, and may be obtained using, for example, a calculation formula. Note that the initial operation execution time P includes a time (such as 14 seconds) other than 28 [seconds], as described above, for example, when the stabilization 2 is not executed, the initial operation overall time P may change. Because there is. Further, when performing the heater power value resetting process for resetting the reference power value Wb during execution of the initial operation as will be described later, the remaining time of the initial operation at that time is replaced with the initial operation execution time P. This is because information is referred to.

  FIG. 6 is a flowchart showing the contents of control processing for warm-up and initial operation. The process of FIG. 5 is executed by the control unit 60 when the power is turned on.

  First, a heater usable power calculation process (step S1) and a heater power value setting process (step S2) are executed. These processes are processes for setting in advance a power value to be supplied to the heater 53 during the warm-up before the initial operation and the warm-up are performed in parallel, and the power value set here is Actually, it is supplied to the heater 53 at the time of warm-up.

  FIG. 7 is a flowchart showing the contents of a subroutine of the heater usable power calculation process. As shown in the figure, initial operating power information is acquired (step S11). In the present embodiment, the initial operation information stored in the initial operation information storage unit 107 is read. In addition, as the said acquisition, you may acquire by receiving the input of initial operation information, or receiving from another apparatus, for example.

  With reference to the initial operation information, an initial operation execution time P is obtained according to the content of the execution item of the initial operation (step S12). In the example of FIG. 3, P = 28 [seconds]. If the item executed in the initial operation is unchanged, a predetermined value is read as the initial operation execution time P. Then, the power usage upper limit value Wmax is acquired (step S13). Specifically, the power usage upper limit information stored in the power upper limit information storage unit 108 is read. In the above example, Wmax = 1500 [W].

  Subsequently, the time transition of the heater usable power value (power value that can be supplied to the heater 53 during the initial operation) Wa is calculated from the initial operating power information and the power use upper limit value Wmax (step S14). Specifically, a value obtained by subtracting the system power Ws during the initial operation from the power usage upper limit value Wmax is obtained as Wa. This will be described more specifically with reference to FIG.

  FIG. 8A shows an area other than the system power Ws (hatched portion) used during the initial operation when the power usage upper limit Wmax is 1500 [W] and the system power is Ws (same as in FIG. 4). It is a figure which shows that (grid-like part) is equivalent to heater usable electric power value Wa.

  FIG. 8 (b) is a graph showing only the grid-shaped portion of FIG. 8 (a), which is shown as a graph of heater usable power during the initial operation, and FIG. 9 is a graph of FIG. 8 (b). It is the figure which converted into a table format and showed the corresponding relationship of the initial operation time and heater usable electric power value.

  As shown in both figures, since the value of the system power Ws is not constant during execution of the initial operation, Wa can be taken up to 1450 [W] at a certain time, for example, 2 seconds, but 900 [W at the time of 6 seconds. It can be seen that it can only be taken. By obtaining the information shown in the graph of FIG. 8B or the table of FIG. 9 as the time transition of the heater usable power value Wa, how many watts after the start of the initial operation, how many watts, and the use power upper limit value Wmax It can be known before starting the initial operation whether the heater 53 can be supplied without exceeding.

  FIG. 10 is a flowchart showing the contents of a subroutine of the heater power value setting process.

  As shown in the figure, the surface temperature T of the fixing roller 51 is detected (step S21). This detection is performed by receiving a detection signal from the temperature detection sensor 54.

  Next, the heater supply reference power value information stored in the heater supply reference power value information storage unit 109 is read, and the reference power value Wb corresponding to the surface temperature T of the fixing roller and the initial operation execution time P is obtained (step S22). ). According to the example of FIG. 5, if T = 30 [° C.] and P = 28 [seconds], Wb is 1150 [W].

  Then, the entire initial operation time P is divided into unit times, here, every one second, and the heater usable power value Wa and the heater supply reference power value Wb are compared for each section (step 23). It is determined whether or not there is a section (power shortage section) that will be Wa <Wb (step 24). This determination method will be specifically described with reference to FIG.

  FIG. 11A is a graph illustrating an example of an assumed transition of time between the heater usable power value Wa and the heater supply reference power value Wb when the initial operation is executed.

  For example, at the time of 2 seconds from the start of the initial operation, Wa = 1450 [W] and Wb = 1150 [W], so that Wa> Wb. On the other hand, at the time of 7 seconds, since Wa = 900 [W] and Wb = 1150 [W], the relationship of Wa <Wb is established. Such a large / small judgment is executed in units of one second. Here, Wa <Wb means that the heater can be supplied up to the heater usable power value Wa in the section, but cannot be supplied up to the heater supply reference power value Wb (if Wb is supplied, the use power upper limit value Wmax of 1500). [W] is exceeded).

  As described above, the heater supply reference power value Wb is obtained in anticipation that the warm-up and the end timing of the initial operation can be matched if the power value Wb is kept constant and supplied during the initial operation. Is. Therefore, if there is a section where Wa <Wb, the amount of power is insufficient in that section compared to the case where the original power value Wb is supplied. As a result, the amount of heat generated by the heater 53 is also smaller than when the power value Wb is supplied, and the time required for the surface temperature of the fixing roller 51 to reach the target temperature becomes longer. Will not be finished yet.

  Therefore, when the section where Wa <Wb is determined as the power shortage section, the existence of the power shortage section is determined and it is determined that the power shortage section exists ("YES" in step S24). The process of allocating electric power (steps S25 to S27) is performed so as to compensate for some other section.

  That is, in step S25, the total insufficient power amount Wt is calculated. The calculation of the total power shortage Wt is performed by calculating the difference between Wa and Wb for each power shortage section and adding the differences between the sections. In the example of FIG. 11A, the area S0 of the shaded portion between 4 and 12 seconds corresponds to the total insufficient power amount Wt. Here, for example, it is assumed to be equivalent to about 900 W.

  In step S26, an amount ΔW for allocating the amount of power corresponding to the total insufficient power amount Wt to other sections other than the insufficient power section is calculated for each section. Specifically, ΔW can be calculated, for example, by dividing (averaging) the total power shortage Wt by the total time of other sections. In the case of the example in FIG. 11A, the other sections are sections of 2 to 4 seconds and 12 to 28 seconds, and the total time is 18 seconds, so ΔW is about 50 [W].

  In step S27, the heater supply power value is set to Wa for a section in which power is insufficient, and to Wc for other sections, a value Wc obtained by adding ΔW to Wb.

  FIG. 11B is a diagram showing a graph of the set heater supply power value, and FIG. 12 is a table format showing the correspondence between the initial operation time and the heater supply power value shown in the graph of FIG. FIG.

  As shown in both figures, in the section where power is insufficient (4 to 12 seconds), the heater usable power value Wa becomes the heater supply power, and other sections (2 to 4 seconds, 12 to 28 seconds). ), A heater supply power value is a value Wc obtained by adding ΔW (shaded portion) to the heater supply reference power value Wb. In the figure, the amount of electric power (area) in the shaded portion is equal to the total insufficient power amount Wt (area S0 of the shaded portion in FIG. 11A).

  If the power is allocated in this way, the amount of power to be supplied to the heater 53 from the start to the end of the initial operation can be made the same as the amount of power when the constant value Wb is supplied. Even if there is a section where Wa <Wb due to the execution of the operation, it is possible to make the end timings of both the warm-up and the initial operation substantially coincide.

  The time transition data of the graph shown in FIG. 11B or the table shown in FIG. 12 is stored. Thereby, the heater supply power value is set (determined).

  In the above allocation method, the power consumption in the section where power is insufficient (4 to 12 seconds) corresponds to the power usage upper limit value Wmax, which is just below the upper limit. Therefore, the total insufficient power amount Wt is calculated so that a certain margin can be obtained, for example, a total amount of insufficient power amount Wt obtained by adding a predetermined value to the amount of power corresponding to the area of the shaded portion in FIG. can do. In this case, although the allocation amount increases by the added predetermined value, it is possible to prevent actual power consumption from reaching the upper limit. Alternatively, a method may be employed in which the power usage upper limit value Wmax itself is set in advance to a value that is somewhat lower than the power supply rating.

  Returning to FIG. 10, if it is determined in step S24 that there is no power shortage section where Wa <Wb, the heater supply power is set to the heater supply reference power value Wb (step S28), and the process returns. The setting in this case is performed, for example, by storing the data with the heater supply reference power value Wb as a constant value.

  Returning to FIG. 6, in step S3, driving of the fixing roller 51 is started, in step S4, an initial operation is started, and in step S5, the timer 105 is started. Here, the initial operation in step S4 is executed according to the order in which the operation items indicated in the initial operation information acquired in step S11 are determined.

  Then, heater control (warm-up) for supplying power to the heater 53 is started (step S6). As a result, the initial operation and the warm-up are executed in parallel.

  FIG. 13 is a flowchart showing the contents of the heater control subroutine.

  As shown in the figure, data of the target temperature T0 of the fixing unit 50 is acquired (step S31). This acquisition is performed by reading information indicating the target temperature stored in the fixing target temperature storage unit 106.

  The current surface temperature T of the fixing roller 51 is detected (step S32). This detection is performed by the same method as the processing in step S21.

  It is determined whether or not temperature T <T0 (step S33). Normally, the temperature T <T0 should be maintained until the warm-up is completed.

  If it is determined that the temperature T <T0 (“YES” in step S33), the heater supply corresponding to the elapsed time from the start of the initial operation is referred to with reference to the heater supply power value set in the heater power value setting process. The inverter circuit 55 is instructed to supply power so that power is supplied to the heater 53 (step S34). Here, the elapsed time from the start of the initial operation is grasped by reading the count value of the timer 105.

  For example, when the elapsed time is 2 seconds, the heater supply power value corresponding to the elapsed time from the start of the initial operation is 1200 [W] according to the graph of FIG. 11B (or the table of FIG. 12). The power of 1200 [W] is supplied to 53.

  Then, it is determined whether or not the initial operation performance rate is 50 [%] (step S35). Here, the initial operation performance rate indicates the ratio of the actual operation time to the initial operation execution time P. For example, if P = 28 seconds, the time when 14 seconds have elapsed from the start of the initial operation is 50 [%]. It is said.

  If it is determined that the initial operation performance rate is not 50 [%] (“NO” in step S35), the process returns. In this case, returning to FIG. 6, it is determined in step S7 whether or not the initial operation has been completed. This determination is made by referring to the count value by the timer 105 whether or not the initial operation execution time P has elapsed since the start of the initial operation.

  If it is determined that the initial operation is not completed, that is, it is being executed (“NO” in step S7), the process returns to the heater control process (step S6).

  Thus, the processes after step S31 are repeatedly executed until the initial operation ends. Meanwhile, the heater 53 has a power corresponding to the heater supply power value corresponding to the elapsed time from the start of the initial operation, for example, 1200 [W] for 2 to 4 seconds, 1110 [W] for 5 to 4 seconds, 5 900 [W] is supplied for ˜8 seconds, 1100 [W] is supplied for 8 to 12 seconds, and 1200 [W] is supplied for 12 to 14 seconds. The above process is repeated every 100 [milliseconds], for example. As a result, the temperature of the fixing roller 51 is raised to the target temperature. In this sense, the control unit 60, the inverter circuit 55, and the like, when performing the heater control process in step S6, control the power supplied to the heater to warm up the fixing member from the detected temperature to the target temperature. It can be said that it functions as a power supply control means to perform.

  When it is determined that the initial operation performance rate has reached 50 [%] (“YES” in step S35), heater power value resetting processing is executed (step S37). This process is a process of resetting the heater power supply value, and is executed only once when the initial operation performance rate reaches 50 [%].

  FIG. 14 is a flowchart showing the contents of a subroutine of the heater power value resetting process. Since the content of the process is basically the same as the heater power value setting process (step S2), the description will focus on the different parts, and the description of the same parts will be omitted. In the same figure, the same steps as those in the heater power value setting process are denoted by the same reference numerals and a part thereof is omitted.

  As shown in the figure, the current surface temperature T of the fixing roller is detected (step S21). Then, the heater supply reference power value information stored in the heater supply reference power value information storage unit 109 is read, and a reference power value Wb ′ corresponding to the surface temperature T of the fixing roller and the initial remaining operation time Pr is obtained (step S38). ). Here, the initial operation remaining time Pr indicates the length of the remaining operation time in the entire initial operation time P. For example, assuming that the total initial operation time P = 28 [seconds], the initial operation remaining time Pr is 14 [seconds] since the initial operation performance rate is 50 [%].

  With reference to the heater supply reference power value information, a reference power value Wb ′ corresponding to the current surface temperature T of the fixing roller 51 and the remaining initial operation time Pr is obtained. For example, if the initial operation total time P is replaced with Pr in FIG. 5 and the current temperature T = 110 [° C.], the reference power value Wb ′ becomes 1200 [W].

  Subsequently, the same processing as steps S23 to S28 is executed. At that time, the reference power value Wb is replaced with Wb ′, and the time transition of the heater supply power value is obtained for the section from 14 to 28 seconds of the entire initial operation time P. Then, the obtained power value is reset as a new heater supply power value, for example, overwritten and stored (step S39), and the process returns.

  In the case of the example of FIG. 11A, if the reference power value Wb ′ = 1200 [W], Wa = 1300 [W] after 14 seconds, so there is a section in which Wa <Wb ′ has a relationship. It does not exist, and 1200 [W] of the reference power value Wb ′ becomes the heater supply power value as it is. In this case, the same value as the initial heater supply power value obtained before the start of the initial operation is reset.

  For example, if the current temperature T is 150 [° C.], the reference power value Wb ′ is 900 [W] from FIG. 5, and this 900 [W] is reset as the heater supply power value. As an example of the case where the reset value is smaller than the initial set value in this way, the actual temperature increase rate of the fixing roller 51 is fast, and if power is supplied with the original set value, the warm-up is faster. There may be cases where the process ends. By resetting the heater power supply value, it is possible to further reduce the difference between the initial operation and the warm-up end timing.

  Further, for example, when the current temperature T is lower than 110 [° C.], the temperature rise of the fixing unit 50 is delayed from the previous schedule, and is larger than 1200 [W] and 1300 [W] or less. For example, Wd (one-dot chain line) in FIG. 11B is reset.

  In consideration of the above cases, the initial operation and warm-up end timing can be set by resetting the heater power supply value at the intermediate point in the present embodiment during the actual execution of the initial operation. It becomes possible to make it easier to match.

  Returning to FIG. 13, in the heater control process, after the heater supply power value is reset, the power supply amount is controlled based on the reset heater supply power value (step S34).

  Immediately before the end of the initial operation, for example, if it is determined that the temperature T <T0 is not satisfied, that is, T ≧ T0 (“NO” in step S33), the surface temperature of the fixing roller 51 is equal to or higher than the target temperature. Therefore, the power supply to the heater 53 is stopped (step S36), and the process proceeds to step S35. When the routine is completed and it is determined again in step S33 that the temperature T <T0 (“YES” in step S33), the power supply to the heater 53 is resumed (step S34).

  If it is determined in step S7 in FIG. 6 that the initial operation has been completed, the timer 105 is reset (step S8), and the process ends. At this point, the heater control by the heater control process in step S6 should be completed, and the surface temperature of the fixing roller 51 should reach the target temperature. It is also assumed that the target temperature has not been reached. In such a case, warm-up is continued. Since the initial operation has already been completed, it is not necessary to consider the power consumed in the initial operation, and for example, the maximum 1450 [W] can be supplied to the heater 53.

  When both the initial operation and the warm-up are completed, the state shifts to a ready state where copying is possible, and copying (image formation) is executed in accordance with an instruction from the user.

  As described above, in this embodiment, when power is supplied to the heater so that the initial operation and the warm-up end time coincide with each other, if there is a section exceeding the rating of the power supply, Lowers the power so that it falls below the rating, and allocates the amount of power that is deficient by lowering the power within the range below the rating to the section that does not exceed the rating, and adds the power value to be supplied to the heater. Since it is set in advance, it is possible to suppress the power consumption of the fixing unit while preventing the power supply rating from being exceeded during actual warm-up. Needless to say, values such as initial operation execution time, system power, and power upper limit value are not limited to those described above, and values corresponding to the configuration of each device are set.

  The present invention is not limited to the image forming apparatus, and may be a power supply method for supplying power to the heater of the fixing unit. Furthermore, the method may be a program executed by a computer. The program according to the present invention includes, for example, a magnetic disk such as a magnetic tape and a flexible disk, an optical recording medium such as a DVD-ROM, DVD-RAM, CD-ROM, CD-R, MO, and PD, and a flash memory recording medium. It can be recorded on various computer-readable recording media, and may be produced, transferred, etc. in the form of the recording medium, wired and wireless various networks including the Internet in the form of programs, In some cases, the data is transmitted and supplied via broadcasting, telecommunication lines, satellite communications, or the like.

[Modification]
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and the following modifications may be considered.

  (1) In the above embodiment, in step S26 of the heater power value setting process, the total insufficient power amount Wt is averaged and allocated to other sections other than the power shortage section. However, if the shortage can be supplemented, averaging is performed. It is not limited to the method of doing.

  For example, as shown in the graph of FIG. 15 (table of FIG. 16), the amount of power supplied to the heater 53 can be increased in the first half of the initial operation, and the latter half can be reduced accordingly. In the example of the figure, the supplied power decreases with time after 15 seconds and becomes smaller than the heater supply reference power value Wb after 21 seconds (in the figure, the areas S1 and S2 are the same). So that the slope of the power value is set.). In this way, if the power value to be supplied is set so that the ratio of the allocation amount is larger in the first half section than in the second half later, the supply power can be afforded in the second half, and the actual warm Even when the temperature rise of the fixing unit 50 becomes delayed from the scheduled time, it is easy to recover the delay in the temperature rise when resetting the power value by the heater power value resetting process.

  In the above description, the same amount as the total power shortage Wt is assigned to other sections other than the power shortage section, but is not limited to the same. For example, depending on whether the allocation method is average (FIG. 4) or variable (FIG. 15), the temperature rise rate of the fixing roller 51 changes from the case where the constant value Wb is continuously supplied from the start to the end of the warm-up, and the initial operation. If it is assumed that the warm-up cannot be completed at the same time, an appropriate relationship between the total power shortage Wt and the amount of power to be added, for example, taking a large amount of power to be added in advance Required from experiments.

  (2) In the above embodiment, first, the reference power value Wb (constant value) is set (step S22), and the sum of the system power Ws (the power that will be required to execute the initial operation excluding the heater 53) is used. For a section that is assumed to exceed the power upper limit value Wmax, by allocating the excess power amount to another section (correction of the reference power value Wb) (steps S23 to S27), the time transition of the power to be supplied to the heater 53 However, if the time transition of the heater power supply value can be determined in advance from experiments so as not to exceed the upper limit value of power usage due to the relationship with the time transition of the system power Ws, it is limited to the above method. It will never be done.

  For example, as a method of setting the reference power value Wb, instead of making the time transition of the reference power value Wb constant, the time transition is set such that the value is large in the first half of the warm-up period and small in the second half. It is also possible to set so that the magnitude relationship of the values is reversed.

  Further, without setting the reference power value Wb, it is required as the power supplied to the heater 53 so that the end time of both the initial operation and the warm-up match from the current temperature of the fixing unit 50 and the initial operation time. The total amount of power that would be obtained is acquired, and the amount of power that is acquired is preferentially increased in a section where the system power Ws is small (a section where there is a margin in power) within a range that does not exceed the power usage upper limit Wmax. It is also possible to determine the supply value as described above and determine the time transition of the determined power value as the time transition of the heater supply power.

  (3) In the above embodiment, both the initial operation and the warm-up are started substantially simultaneously. However, for example, the warm-up may be started in the middle of the initial operation, and both may be performed in parallel thereafter. In this case, in the heater usable power calculation process, initial operation information is acquired for the section from the start to the end of the warm-up (step S11), and the section is obtained as the initial operation execution time P (step S11). S12). For example, if the warm-up start time is 14 seconds, information from 14 seconds to 28 seconds is acquired as the initial operation information, and the initial operation execution time P is set to 14 seconds. In step S14, the heater usable power Wa is obtained from the acquired initial operation information. In the heater power value setting process, the same process as the heater power value resetting process may be executed. Conversely, the present invention can be similarly applied to the case where the initial operation is started during warm-up. In this sense, making both the initial operation and the warm-up parallel is not limited to the simultaneous start, but is used in a concept including the case where one starts first.

  (4) In the above embodiment, the initial operation and warm-up are performed when the power to the apparatus is turned on. However, the present invention is not limited to this. For example, it may be executed immediately after recovery from a trouble such as a paper jam (jam) or a failure, or immediately after the end of maintenance.

  (5) In the above embodiment, an example in which the image stabilizing operation, the initial operation of the image reader unit 12 and the finisher 14 are executed as the initial operation has been described. However, the execution items are not limited to these. Any item that needs to be executed before image formation may be used, and the items may be executed sequentially or in combination so that at least a part of the execution time period overlaps. The execution order may be determined in advance or may be changed as appropriate. Further, whether or not execution is necessary is determined by the apparatus state. For example, when there is little variation in the apparatus environment (temperature and humidity, etc.), it is possible not to execute only image stabilization.

  Furthermore, only one of them may be executed as the initial operation. When items to be executed change, for example, initial operation information may be stored in advance for each combination of items, or generated according to the combination when initial operation information is acquired (step S11). Also good. The value of the initial operation execution time P is determined according to the execution item and order.

  (6) In the above embodiment, the heater power value resetting process is performed only once when the initial operation performance rate is 50% in step S35 of the heater control processing. The number of times is not limited to this. For example, the processing may be executed every 10%. As the number of executions increases, the CPU processing load increases accordingly, but the difference between the expected temperature rise time of the fixing roller 51 and the actual time becomes smaller, and it becomes easier to match the initial operation and the warm-up end timing. In addition, if the apparatus configuration is such that the difference hardly occurs, the heater power value resetting process may not be performed.

  (7) In the above embodiment, the initial value is set so that the sum of the power supply value that will be required for the execution of the initial operation and the power supply value to be supplied to the heater 53 does not exceed the rating of the commercial power supply 19 as the upper limit value. Although the time transition of the supplied power value is determined in advance for the operation and warm-up, it may be assumed that it does not become predetermined according to the fluctuation of the power supply voltage. Therefore, it is possible to provide a measuring means for measuring the power value actually consumed by the apparatus itself and reset the heater supply power value according to the measurement result.

  Specifically, during the initial operation and the warm-up, the power consumption measurement (actual measurement) value is compared with the magnitude of the previous calculation value (the sum of the system power Ws and the heater supply power value). If the measured value is less than or equal to the calculated value from the comparison result, the warm-up is continued as it is.

  On the other hand, when the measured value is higher than the calculated value, an amount corresponding to the difference between the measured value and the calculated value, for example, a value obtained by subtracting the value of the difference itself from the current upper limit value is set as the new upper limit value. More specifically, if the current upper limit value is 1500 [W] and the difference is 50 [W], 1450 [W] is set as a new upper limit value, and the heater can be used by performing the same process as step S14. Recalculate the time transition of the power Wa.

  Subsequently, the same process as the heater power value resetting process (step S37) is performed, the initial operation time (remaining time) after the current time is replaced with the initial operation remaining time Pr, and the heater supply power value is reset. The reset heater supply power value is supplied to the heater 53. This is advantageous when the apparatus is installed in an environment where voltage fluctuations or the like are likely to occur due to power supply circumstances.

  (8) In the above embodiment, an example in which the image forming apparatus according to the present invention is applied to a tandem color digital copying machine has been described, but the present invention is not limited to this. Regardless of color or monochrome image formation, any image forming apparatus that performs initial operation and fixing unit warm-up in parallel can be applied to, for example, a printer, FAX, MFP (Multiple Function Peripheral), etc. It does not have to be arranged. Moreover, although the example which applied the thing of the electromagnetic induction heating system as the fixing | fixed part 50 was demonstrated above, it is not restricted to this system. The present invention can be generally applied to a fixing device that heat-fixes an unfixed image on a sheet using a fixing member such as a fixing roller that is heated by a heater whose calorific value varies according to the supplied power.

  The contents of the above embodiment and the above modification may be combined.

  The present invention can be widely applied to an image forming apparatus having a fixing unit that thermally fixes a formed image on a sheet.

1 is a diagram illustrating an overall configuration of a copying machine. It is a figure which shows the structure of the control part with which a copying machine is equipped. It is a figure which shows the example of the content of initial operation information. It is a figure which shows the timing chart of the time transition of the supply electric power at the time of initial stage operation | movement. It is a figure which shows the example of the content of heater supply reference | standard electric power value information. It is a flowchart which shows the control processing content of warm-up and initial operation. It is a flowchart which shows the content of the subroutine of a heater usable electric power calculation process. It is a figure which shows the time transition of the system electric power Ws used during an initial stage operation, and the heater usable electric power value Wa. It is the figure which showed the correspondence of initial operation time and heater usable electric power value in a table format. It is a flowchart which shows the content of the subroutine of a heater electric power value setting process. (A) is a figure which shows the relationship of the time transition of heater usable electric power value Wa and heater supply reference electric power value Wb, (b) is a figure which shows the graph of heater supply electric power value. It is the figure which showed the correspondence of initial operation time and heater supply electric power value in a table format. It is a flowchart which shows the content of the subroutine of heater control. It is a flowchart which shows the content of the subroutine of a heater electric power value reset process. It is a figure which shows another graph of heater supply electric power value. It is the figure which showed the correspondence of initial operation time and another heater supply electric power value in a table format.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copy machine 13 Printer part 50 Fixing part 51 Fixing roller 53 Electromagnetic induction coil 54 Temperature detection sensor 55 Inverter circuit 60 Control part 101 CPU
106 Fixing target temperature storage unit 107 Initial operation information storage unit 108 Power upper limit value information storage unit 109 Heater supply reference power value information storage unit

Claims (6)

An image forming apparatus that forms an image on a sheet and thermally fixes the formed image to the sheet using a fixing member of a fixing unit,
A heater that heats the fixing member and varies a calorific value in accordance with a magnitude of supplied power;
Detecting means for detecting the temperature of the fixing member;
Power supply control means for controlling the power supplied to the heater to warm up the fixing member from a temperature detected by the detection means to a target temperature necessary for heat fixing;
Obtaining means for obtaining a time transition of a power supply value that is required for execution of an initial operation excluding power supplied to the heater, which is required before the start of image formation,
The power supply control means includes
Setting means for performing the initial operation and the warm-up in parallel , and setting a constant electric power value to be required as the electric power supplied to the heater in order to make the end times of both the initial operation and the warm-up coincide. When,
If there is a section where the sum is expected to exceed a predetermined upper limit when the power that will be required for the execution of the initial operation and the set constant power supply are performed in parallel, the section The value of the constant power is reduced, and the amount of power corresponding to the reduced amount is compensated by increasing the value of the constant power in other sections other than the section so that the sum is less than or equal to the upper limit value. And a correcting means for correcting the value of the constant power.
An image forming apparatus , wherein a time transition of the corrected electric power is determined as electric power supplied to the heater . The setting means includes
How much electric power can be supplied constantly to the heater with respect to the time required for the initial operation and the temperature detected by the detection means, the end of both the initial operation and the warm-up can be matched. referring to the information indicating the image forming apparatus according to claim 1, characterized in that setting the value of constant power to the heater. The setting means includes
During execution of the initial operation, a constant power value to be required as power supplied to the heater is set to match the end time of both the initial operation and warm-up for the remaining period until the end of the initial operation. Reset
The correction means includes
When the resetting is performed, the upper limit value is the sum of the reset constant power value and the power value that will be required for the remaining period of the initial operation over time. the image forming apparatus according to claim 1 or 2, characterized in that to correct the reset value of the constant power to be less than. The correction means includes
The image forming apparatus according to any one of claims 1 to 3, characterized in that to compensate by assigning by averaging the electric power amount corresponding to the lowered amount on the other section. The correction means includes
The amount of electric power corresponding to the lowered amount is compensated by allocating to the other section, and the ratio of the allocation amount is more temporal in the first unit section than in the first unit section among the other sections. the image forming apparatus according to any one of claims 1 to 3 that is characterized by greater than a second unit section later. It has a measuring means to measure the power that the device is actually consuming,
The power supply control means includes
A time transition of a value obtained by summing a power supply value that will be required for execution of the initial operation and a power supply value to the determined heater is obtained, and a measured value by the measuring unit during execution of the initial operation and warm-up If the value is larger than the calculated total value, a value obtained by subtracting the amount corresponding to the difference between the measured value and the total value from the predetermined upper limit value is set as a new upper limit value. Using the upper limit value, the time transition of the power supply value to the heater is reset for the remaining time of the initial operation, and the power supplied to the heater is changed according to the time transition of the reset power supply value. the image forming apparatus according to any one of claims 1 to 5, characterized in that control.

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