JP2006235043A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device reducing the non-urgent power consumption, and supplying the necessary power to a fixing unit appropriately. <P>SOLUTION: The image forming device for fusing a toner image formed on a paper by a fixing unit detects a temperature of the fixing unit, and decides the number of papers to be fed per unit time on the basis of the detected temperature and the power which can be inputted to the fixing unit (Step S2). When the number of papers to be fed per unit time reaches the predetermined value or less (YES in the step S3), operations of the units other than the fixing unit, such as an image reading unit and a post-processing unit are restricted at least for a predetermined time, and the printing operation is carried out (Step S4). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that heats and fixes a toner image formed on a recording material such as a copying machine or a printer by a fixing unit.

  In general, an image forming system that forms a toner image on a recording material by an electrophotographic method consumes a large amount of power. Therefore, in designing the system, a design that conforms to the power restriction rules established by public institutions in each country, including the Domestic Electricity Business Act, is required. For example, in Japan, a design that limits power consumption within 1500 W (100 V × 15 A) is required.

  On the other hand, the electrophotographic image forming system is multi-functional, and in addition to the original image forming unit such as exposure, development, toner image transfer, and fixing on a photoconductor, A plurality of units such as a post-processing unit for performing paper folding processing and a punching unit for punching paper are provided.

  Therefore, the power consumption tends to be larger than that of a system including only the main body image forming unit. However, even an image forming system including a plurality of units has the same power limit as a simple system. In order to adapt the image forming system to such a power limit, the power distribution to each unit must be performed.

  By the way, depending on the image forming mode, there are cases where all the units are operated and cases where there are unused units. For example, if paper is fed from the manual paper feed tray, the large-capacity paper feed unit does not need to be operated, and depending on how functions are selected such as post-processing, punching, and cutting, there are units that are not operated. In view of such circumstances, various control methods as disclosed in Patent Documents 1 to 5 have been conventionally proposed in consideration of power supply to a fixing unit with high power consumption.

  In the conventional control method, the electrode distribution of each unit is set in advance according to the image forming mode, and when the corresponding mode is selected, the power is distributed to each unit by a method of allocating the determined power. Most of them. Furthermore, by providing means for detecting the power consumption of each unit, the power distribution to each unit is changed based on the actual power consumption.

  For example, in the control described in Patent Document 1, if the continuous sheet feeding is started in a state where the fixing unit is not sufficiently warmed, such as immediately after the power supply to the system is turned on, the temperature of the fixing unit falls below a temperature at which the fixing property can be secured. Therefore, the temperature reduction of the fixing unit is prevented by the control for reducing the number of sheets to be passed per unit time and the control for limiting the number of sheets to be continuously passed. At this time, since the number of sheets passed through the image forming system is reduced, each unit has a time in which operation time is left and the operation is stopped. If power is redistributed during the stop period of each unit, the power supplied to the fixing unit can be increased.

However, in the image forming system, since the power is switched in accordance with the operation other than the fixing unit, the necessary power cannot be supplied to the fixing unit when the power is required, and each unit is frequently operated / stopped. Therefore, there is a problem that power loss occurs depending on the power switching timing.
JP-A-10-254306 JP 2000-321923 A JP 2000-214709 A JP 2002-244507 A JP-A-11-219066

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can reduce the urgent power consumption and supply the necessary power to the fixing unit in a timely manner.

  To achieve the above object, according to a first aspect of the present invention, in an image forming apparatus for heating and fixing a toner image formed on a recording material by a fixing unit, a power switching unit for switching power supplied to the fixing unit; Based on the temperature detection means for detecting the temperature of the fixing unit, the detection result by the temperature detection means, and the power that can be input to the fixing unit at the time of image formation, the paper feed control is performed and the paper feed control is below a predetermined value. And a control means for limiting the operation of the units other than the fixing unit at least for a predetermined time.

  In the image forming apparatus according to the first aspect of the invention, paper feed control is performed based on the temperature of the fixing unit. The paper feed control is, for example, the number of sheets that can be passed per unit time or the number of sheets that can be continuously passed, and when this number falls below a predetermined value (that is, when the limit of paper feed control becomes large). By restricting the operation of units other than the fixing unit (for example, the operation of the image reading unit and / or the operation of the post-processing unit with respect to the image-formed recording material) for at least a predetermined time, the urgent power consumption is reduced. It is possible to supply the power of the minute to the fixing unit.

  In the image forming apparatus according to the first aspect of the present invention, it is preferable that the temperature detecting means detects the temperature of the inner surface of the fixing unit cover above the heating source of the fixing unit or the surface of the roller having no heating source. By detecting the temperature of the part away from the heat source, it is possible to detect the warming state of the entire fixing unit. The temperature detection means can also serve as an abnormal temperature detection means.

  According to a second aspect of the present invention, there is provided an image forming apparatus for heating and fixing a toner image formed on a recording material by a fixing unit, a power switching means for switching power supplied to the fixing unit, and a heating source for the standby fixing unit. When a paper feed control is performed based on a calculation means for calculating the energization ratio to the power supply, a calculation result by the calculation means, and a power that can be input to the fixing unit during image formation, and the paper feed control falls below a predetermined value And control means for limiting the operation of units other than the fixing unit for at least a predetermined time.

  In the image forming apparatus according to the second aspect of the invention, sheet feeding control is performed based on the energization ratio of the heating source to the waiting fixing unit and the power that can be input to the fixing unit. The paper feed control is, for example, the number of sheets that can be passed per unit time or the number of sheets that can be continuously passed, and when this number falls below a predetermined value (that is, when the limit of paper feed control becomes large). By restricting the operation of units other than the fixing unit (for example, the operation of the image reading unit and / or the operation of the post-processing unit with respect to the image-formed recording material) for at least a predetermined time, the urgent power consumption is reduced. It is possible to supply the power of the minute to the fixing unit.

  In the image forming apparatus according to the second aspect of the present invention, the control unit may stop the energization to the fixing unit by determining the abnormal energization when the calculation result of the energization ratio by the calculation unit is larger than a predetermined value. .

  According to a third aspect of the present invention, there is provided an image forming apparatus in which a toner image formed on a recording material is heated and fixed by a fixing unit, from a power switching means for switching power supplied to the fixing unit, and from power-on to the image forming apparatus A storage unit that stores the history of the sheet, and the sheet storage control based on the history stored in the storage unit and the power that can be input to the fixing unit at the time of image formation. And control means for limiting the operation of units other than the fixing unit for at least a predetermined time.

  In the image forming apparatus according to the third aspect of the invention, sheet feeding control is performed based on the history since the power was turned on to the image forming apparatus and the power that can be input to the fixing unit. Here, the history is, for example, the temperature of the fixing unit when the power is turned on, the elapsed time since the power is turned on, and / or the number of sheets passed since the power is turned on. The paper feed control is, for example, the number of sheets that can be passed per unit time or the number of sheets that can be continuously passed, and when this number falls below a predetermined value (that is, when the limit of paper feed control becomes large). By restricting the operation of units other than the fixing unit (for example, the operation of the image reading unit and / or the operation of the post-processing unit with respect to the image-formed recording material) for at least a predetermined time, the urgent power consumption is reduced. It is possible to supply the power of the minute to the fixing unit.

  The image forming apparatus according to a third aspect of the present invention further comprises temperature detecting means for detecting the temperature of the fixing unit, and the control means performs paper feed control based on the temperature detected by the temperature detecting means when the power is turned on. It may be changed.

  In the image forming apparatuses according to the first, second, and third inventions, the control unit transfers to another image forming apparatus when the number of sheets to be passed per unit time or the number of continuously passed sheets is equal to or less than a predetermined value. Image data may be transferred. By transferring image data to another image forming apparatus and executing image formation with the transferred image forming apparatus, image formation can be efficiently performed using a network.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Schematic configuration of image forming system, see FIGS. 1 and 2)
FIG. 1 shows a schematic configuration of an image forming system 1 according to the present invention. This image forming system 1 forms a toner image on a sheet by a well-known electrophotographic process, and generally reads an original image by an image forming unit 2 centered on a photosensitive drum 3 and a line sensor such as a CCD. The unit 10 includes a large-capacity paper feeding unit 15, a fixing unit 20, and a post-processing unit 30.

  In FIG. 1, an alternate long and short dash line A indicates a sheet passing path, and the sheets fed one by one from the large capacity sheet feeding unit 15 are transferred by the fixing unit 20 after the toner image is transferred from the photosensitive drum 3. The toner is heat-fixed and conveyed to the post-processing unit 30.

  The post-processing unit 30 includes an electric stapler 31 and a paper stacking tray 32. The image-formed paper is stapled as necessary and discharged / stacked on the tray 32. The tray 32 can be lowered according to the amount of sheets stacked.

  Note that an electrophotographic image forming process by the image forming unit 2, paper feeding / conveying by the paper feeding unit 15, an operation of the post-processing unit 30, and the like are well known in the art, and a description thereof is omitted.

  FIG. 2 shows the control unit of the image forming system, which is configured around the CPU 50. The CPU 50 includes a ROM 51 that stores a control program and a RAM 52 that temporarily stores parameters and the like, and controls the image forming unit 2, the paper feeding unit 15, the fixing unit 20, the post-processing unit 30, and the image reading unit 10.

  Each unit is supplied with power from the power supply 54, and the controller 53 for switching the supplied power is controlled by the CPU 50 as described below.

(Refer to the first embodiment, FIGS. 3 to 8)
In the first embodiment, the temperature of the fixing unit 20 is detected, and sheet feeding control (the number of sheets to be passed per unit time or continuous sheet feeding is possible based on the detected temperature and electric power that can be input to the fixing unit 20 at the time of image formation. Control of the number of sheets) and the operation of other units is limited at least for a predetermined time when the controlled number of sheets to be passed becomes a predetermined value or less. The predetermined value means the number of sheets that can be fixed by the fixing unit 20 without impairing the image quality.

  The fixing unit 20 used in the first embodiment is the one shown in FIG. 3, FIG. 4, or FIG. The fixing unit 20A shown in FIG. 3 includes a heating roller 21 and a pressure roller 23 that incorporate a heat source 22 such as a halogen lamp. A temperature sensor 29 is provided on the inner surface of the upper cover 26 of the fixing unit 20. The sheet is conveyed in the direction of arrow A, and the toner is fixed by heating from the heating roller 21.

  The fixing unit 20B shown in FIG. 4 has basically the same configuration as the fixing unit 20A shown in FIG. 3, and the temperature sensor 29 is arranged in contact with the surface of the pressure roller 23 having no heat source.

  The fixing unit 20 shown in FIG. 5 has an arrangement in which a fixing belt 25 is stretched endlessly between a heating roller 21 having a built-in heat source 22 and a fixing roller 24 and a pressure roller 23 is opposed to the fixing roller 24. It is. The temperature sensor 29 is disposed to face the surface of the fixing belt 25. The sheet is conveyed in the direction of arrow A, and the toner is fixed by heating from the fixing belt 25.

  In the fixing units 20A, 20B, and 20C, the temperature is detected by the temperature sensor 29, and the detection result is input to the CPU 50 shown in FIG. Thus, the temperature sensor 29 does not directly detect the temperature of the heat source 22 but can detect the warming state of the entire unit by detecting the temperature at a location away from the heat source 22. The temperature sensor 29 can also serve as a means for detecting abnormal heating by the heat source 22. In order to detect abnormal heating, the temperature sensor 29 is preferably disposed immediately above the heating roller 21, as shown in FIG.

  Here, the control procedure in the first embodiment will be described with reference to FIGS. In the flowchart shown in FIG. 6, when a print start is instructed (step S1), the unit is determined based on the temperature detected by the temperature sensor 29 (step S7) and the power that can be input to the fixing unit 20 (step S8). The number of sheets passed per time is determined (step S2).

  Determination of the power that can be input to the fixing unit 20 is performed based on the set image mode, and the number of sheets to be passed per unit time is determined with reference to the graph shown in FIG. If the temperature of the fixing unit 20 is increased, the number of sheets to be passed per unit time increases even with the same inputable power. When the temperature is lowered, the number of sheets to be passed is reduced to ensure the fixing performance.

  Next, the determined number of sheets to be passed per unit time is compared with a predetermined value. If the number of sheets to be passed is equal to or less than the predetermined value (YES in step S3), printing is performed while restricting the operations of units other than the fixing unit 20. Is executed (step S4). Here, the predetermined value means that the number of sheets to be passed is preferably increased by increasing the fixing ability by additionally supplying power to the fixing unit 20 even if the operation of other units is restricted because the restriction on the number of sheets to be passed becomes large. .

  On the other hand, if the number of sheets passed in step S2 exceeds a predetermined value (NO in step S3), printing is performed without restricting the operation of other units (step S5). Thereafter, when printing continues (NO in step S6), the process returns to step S2.

  FIG. 7 shows an example of the restricted print process executed in step S4. If the image data read by the image reading unit 10 is stored in the memory (YES in step S11), the operation of the image reading unit 10 is performed. Limit (step S12). On the other hand, when there is no accumulation of image data (NO in step S11), the image reading unit 10 is preferentially operated, and the operation of the post-processing unit 30 is restricted (step S13).

  Thereafter, the power supplied to the fixing unit 20 is changed (step S14). That is, the power consumption of each unit is as shown in Table 1, for example, and the fixing unit 20 can be supplied with an extra power of 100 W for limiting the operation of the image reading unit 10 or the post-processing unit 30. .

  In the first embodiment, when the limit on the number of sheets to be passed per unit time is increased to a predetermined value or less, the operation of the image reading unit 10 or the operation of the post-processing unit 30 is performed for a predetermined time (next printing). By limiting (until NO is determined in step S3 in the operation), the urgent power consumption is reduced, and it is possible to supply the corresponding amount of power to the fixing unit.

(Refer to the second embodiment, FIGS. 9 and 10)
In the second embodiment, the energization ratio to the heating source of the fixing unit in standby is calculated, and the sheet feed control (per unit time) is performed based on the calculated energization ratio and the power that can be input to the fixing unit 20 at the time of image formation. The control of the number of sheets that can be passed or the number of sheets that can be continuously passed) is performed, and when the controlled number of sheets that pass is less than or equal to a predetermined value, the operation of other units is limited at least for a predetermined time. The meaning of the predetermined value in the second embodiment is the same as that in the first embodiment.

  As shown in the flowchart of FIG. 9, the control procedure is as follows. First, when a print start is instructed (step S21), the energization ratio to the heat source 22 of the fixing unit 20 in standby (step S27) and the fixing unit 20 The number of sheets to be passed per unit time is determined based on the input power (step S30).

  The energization ratio is calculated as a ratio of the energization amount to the heat source 22 of the fixing unit 20 with respect to the entire energization amount during standby of the printing operation. If this energization ratio is larger than the predetermined value (YES in step S28), energization to the fixing unit 20 is stopped as abnormal energization (step S29), and the printing operation is terminated. Thus, it is possible to prevent an abnormal situation in which excessive power is supplied to the fixing unit 20 from occurring.

  Determination of the power that can be input to the fixing unit 20 is performed based on the set image mode. Further, the number of sheets to be passed per unit time is determined with reference to the graph shown in FIG. A high energization ratio means that the fixing unit 20 is not warmed. Accordingly, in this case, the number of sheets to be passed is determined to be small.

  Next, the determined number of sheets to be passed per unit time is compared with a predetermined value. If the number of sheets to be passed is equal to or less than the predetermined value (YES in step S23), printing is performed while restricting operations of units other than the fixing unit 20. Is executed (step S24). The predetermined value here is also the same as in the first embodiment.

  On the other hand, if the number of sheets passed in step S22 exceeds a predetermined value (NO in step S23), printing is performed without restricting the operation of other units (step S25). If printing continues thereafter (NO in step S26), the process returns to step S22.

  The restricted print process executed in step S24 is the same as that in FIG. 7 described in the first embodiment. Thus, it is possible to supply the fixing unit 20 with an extra power of 100 W for the operation of the image reading unit 10 or the post-processing unit 30 being restricted.

  In the second embodiment, when the limit on the number of sheets to be passed per unit time is increased to a predetermined value or less, the operation of the image reading unit 10 or the operation of the post-processing unit 30 is performed for a predetermined time (next printing). By limiting (until NO is determined in step S23 in the operation), the urgent power consumption is reduced, and it is possible to supply that much power to the fixing unit.

(Refer to the third embodiment, FIGS. 11 and 12)
In the third embodiment, the history from the power-on to the image forming system is stored, and the sheet feeding control (the number of sheets to be passed per unit time) is based on the stored history and the power that can be input to the fixing unit 20 at the time of image formation. (Or control of the number of sheets that can be continuously fed), and when the number of fed sheets reaches a predetermined value, the operation of other units is limited for at least a predetermined time. The meaning of the predetermined value in the third embodiment is the same as that in the first embodiment.

  As shown in the flowchart of FIG. 11, the control procedure is as follows. First, when a print start is instructed (step S31), a history from power-on (step S37) and power that can be input to the fixing unit 20 (step S38). Based on the above, the number of sheets to be passed per unit time is determined (step S32).

  The contents of the history after power-on are the temperature detected by the temperature sensor 29 when the power is turned on, the elapsed time since power-on, or the number of sheets passed since power-on. These histories are determined as history coefficients with reference to the graph shown in FIG. That is, the history coefficient is determined based on the elapsed time from the power-on or the number of sheets passed and the temperature of the fixing unit 20 at the time of power-on. The detected temperature when the power is turned on indicates the initial warming state of the fixing unit 20, and the current warming state can be obtained based on the elapsed time up to the present time or the number of sheets passed.

  Further, the power that can be input to the fixing unit 20 is determined based on the set image mode, and the number of sheets to be passed per unit time is determined with reference to the graph shown in FIG. A large history coefficient means that the fixing unit 20 is generally warm, and the determined number of sheets to be passed increases.

  Next, the determined number of sheets to be passed per unit time is compared with a predetermined value. If the number of sheets to be passed is equal to or smaller than the predetermined value (YES in step S33), printing is performed while restricting the operations of units other than the fixing unit 20. Is executed (step S34). The predetermined value here is also the same as in the first embodiment.

  On the other hand, if the number of sheets passed in step S32 exceeds the predetermined value (NO in step S33), printing is performed without restricting the operation of other units (step S35). If printing continues thereafter (NO in step S36), the process returns to step S32.

  The restricted print process executed in step S34 is the same as that shown in FIG. 7 described in the first embodiment. Thus, it is possible to supply the fixing unit 20 with an extra power of 100 W for the operation of the image reading unit 10 or the post-processing unit 30 being restricted.

  In the third embodiment, when the limit on the number of sheets to be passed per unit time is increased to a predetermined value or less, the operation of the image reading unit 10 or the operation of the post-processing unit 30 is performed for a predetermined time (next printing). By limiting (until NO is determined in step S33 in the operation), the urgent power consumption is reduced, and it is possible to supply the corresponding amount of power to the fixing unit.

(Refer to the fourth embodiment, FIGS. 13 to 15)
In the fourth embodiment, as shown in FIG. 13, a plurality of image forming apparatuses 1A and 1B can exchange data wirelessly or by wire, or as shown in FIG. 14, a plurality of image forming apparatuses 1A. To 1C and a plurality of computers 60A, 60B are applied to a system that enables data exchange via a network such as a LAN.

  In the system shown in FIG. 13, when the image forming apparatus 1A enters the printing operation and the step S3 in FIG. 6 in the first embodiment, the number of sheets passed per unit time is less than a predetermined value. If determined (see step S43 in FIG. 15, steps S47 and S48 are the same as steps S7 and S8 in FIG. 6), the image data is transferred to the other image forming apparatus 1B (step S44). The image forming apparatus 1B to which the image data has been transferred prints the image data. Thus, image formation can be efficiently performed using a network.

  On the other hand, if the number of sheets passed per unit time exceeds the predetermined value (NO in step S43), the image forming apparatus 1A performs print processing (step S45). Then, when printing continues thereafter (NO in step S46), the process returns to step S42.

  It should be noted that image data may be transferred to another image forming apparatus 1B in the same manner even if YES is determined in step S23 of FIG. 9 in the second embodiment or step S33 of FIG. 11 in the third embodiment. Of course.

  In the system shown in FIG. 14, for example, when the computer 60A outputs a print instruction to the image forming apparatus 1A, the image forming apparatus 1A performs the control shown in FIG. 15, and if YES is determined in step S43, The image data is transferred to one of the other image forming apparatuses 1B and 1C. Therefore, the image data is printed by the transfer destination image forming apparatus 1B or 1C.

(Example of power supply control, see FIG. 16)
Here, an example of power supply control in steps S4, S24, and S34 will be described with reference to FIG. FIG. 16B shows a conventional control example for comparison.

  In the conventional control example shown in FIG. 16B, when the number of passing sheets per unit time decreases at timings t1, t2, and t3, the operation and power supply of the other units 10, 30 and the like also decrease. In addition, since each unit operates in accordance with the sheet passing, the operation / stop is repeated in a short time, and in consideration of the power switching timing, the additional power supply to the fixing unit 20 is limited to a short time. Is done.

  On the other hand, in the control example of the present invention shown in FIG. 16A, when the number of passing sheets per unit time decreases at timings t1, t2, and t3, the operations of the other units 10, 30 and the like are at least performed. Limit by predetermined time X. Therefore, the loss due to the power switching timing is small, and the supply of additional power to the fixing unit 20 can be continued for a relatively long time. Further, it is not necessary to control the number of sheets to be passed more than necessary, and it is possible to prevent a decrease in print productivity.

(Other examples)
The image forming apparatus according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 2 is a block diagram illustrating a control unit of the image forming apparatus. FIG. 3 is a cross-sectional view illustrating a first example of a fixing unit. FIG. 6 is a cross-sectional view illustrating a second example of a fixing unit. FIG. 10 is a cross-sectional view illustrating a third example of a fixing unit. It is a flowchart figure which shows the control procedure (main routine) in 1st Example. It is a flowchart figure which shows the control procedure (subroutine) in 1st Example. 6 is a graph showing the relationship between the detected temperature in the fixing unit and the number of sheets passed per unit time. It is a flowchart figure which shows the control procedure (main routine) in 2nd Example. It is a graph which shows the relationship between the energization ratio in stand-by and the number of sheets passed per unit time. It is a flowchart figure which shows the control procedure (main routine) in 3rd Example. (A) is a graph for calculating a history coefficient, and (B) is a graph showing the relationship between the history coefficient and the number of sheets passed per unit time. It is explanatory drawing which shows the 1st example of the network in 4th Example. It is explanatory drawing which shows the 2nd example of the network in 4th Example. It is a flowchart figure which shows the control procedure (main routine) in 4th Example. (A) is a timing chart showing an example of power supply control during a limiting operation in each embodiment, and (B) is a timing chart showing an example of conventional power supply control for comparison.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming system 2 ... Image forming unit 10 ... Image reading unit 15 ... Large-capacity paper feeding unit 20 ... Fixing unit 29 ... Temperature sensor 30 ... Post-processing unit 50 ... CPU
53 ... Controller 54 ... Power supply

Claims (11)

In an image forming apparatus for heating and fixing a toner image formed on a recording material by a fixing unit,
Power switching means for switching the power supplied to the fixing unit;
Temperature detecting means for detecting the temperature of the fixing unit;
Paper feed control is performed based on the detection result of the temperature detection means and the power that can be input to the fixing unit during image formation, and the operation of units other than the fixing unit is performed when the paper feed control falls below a predetermined value. Control means for limiting at least a predetermined time;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the temperature detecting unit detects a temperature of an inner surface of a fixing unit cover above a heating source of the fixing unit or a surface of a roller having no heating source.   The image forming apparatus according to claim 1, wherein the temperature detection unit also serves as an abnormal temperature detection unit. In an image forming apparatus for heating and fixing a toner image formed on a recording material by a fixing unit,
Power switching means for switching the power supplied to the fixing unit;
A calculating means for calculating an energization ratio to the heating source of the fixing unit during standby;
The sheet feeding control is performed based on the calculation result by the calculating unit and the electric power that can be input to the fixing unit at the time of image formation, and at least the operation of the units other than the fixing unit is performed when the sheet feeding control becomes a predetermined value or less. Control means for limiting a predetermined time;
An image forming apparatus comprising:   5. The image forming according to claim 4, wherein the control unit determines that the energization is abnormal and stops energization of the fixing unit when the calculation result of the energization ratio by the calculation unit is larger than a predetermined value. apparatus. In an image forming apparatus for heating and fixing a toner image formed on a recording material by a fixing unit,
Power switching means for switching the power supplied to the fixing unit;
Storage means for storing a history from power-on to the image forming apparatus;
The sheet feeding control is performed based on the history stored in the storage unit and the power that can be input to the fixing unit during image formation. When the sheet feeding control becomes a predetermined value or less, the operations of the units other than the fixing unit are performed. Control means for limiting at least a predetermined time;
An image forming apparatus comprising:   The image forming apparatus according to claim 6, wherein the history stored in the history unit is an elapsed time from power-on or a number of sheets passed since power-on. And a temperature detecting means for detecting the temperature of the fixing unit.
The control means changes the paper feed control based on the temperature detected by the temperature detection means at power-on;
The image forming apparatus according to claim 6.   The image forming apparatus according to claim 1, wherein the sheet feeding control target is the number of sheets that can be passed per unit time or the number of sheets that can be continuously passed.   The image forming apparatus according to claim 9, wherein the control unit transfers the image data to another image forming apparatus when the number of sheets to be passed per unit time or the number of continuous sheets to be passed becomes a predetermined value or less. apparatus.   7. The operation of a unit other than the fixing unit is an operation of an image reading unit and / or an operation of a post-processing unit with respect to an image-formed recording material. Image forming apparatus.

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