JP2007102008A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of continuing printing operation or warm-up operation, without interrupting the operation of the apparatus or initialization of the apparatus, when power source voltage drops in the power source input part. <P>SOLUTION: The image forming apparatus is equipped with an image forming control part to control operation related to image forming; a power-setting part to previously set the upper limit value and the lower limit value of power consumption in the course of the operation related to image forming; and a power source voltage detection part to detect the power source voltage supplied from the outside, in the course of the operation related to image forming. The image forming control part controls to change the power consumption to be within a range between the upper limit value and the lower limit value so that the power source voltage detected by the power source voltage detection part may be within a predetermined range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that detects a drop in power supply voltage and controls operation.

  In an image forming apparatus using an electrophotographic system, a fixing device for fixing toner consumes a large amount of power, so that a large current flows through a power cable, which may cause a voltage drop. For example, when the image forming apparatus executes continuous printing, the heat of the surface of the fixing roller provided in the fixing device for fixing the toner to the paper is taken away by the toner and the paper. As a result, the surface temperature of the fixing roller is lowered, so that a heat source provided in the fixing device, for example, a heater lamp of about 1200 W is energized to compensate for this. As a result, for example, in the case of an AC power supply with a rated voltage of 100 V, a current of about 12 amperes flows through the power cable connecting the image forming apparatus to the outlet. Therefore, a corresponding voltage drop occurs until the power input unit of the image forming apparatus is reached due to the impedance of the power cable.

  Therefore, in order to avoid the runaway of the microcomputer that controls the operation of the device due to a drop in the power supply voltage, it is detected that the voltage at the power input section has dropped below the reference value and the power supply voltage drop countermeasure process There is one that performs processing to return to the initial state after performing (see, for example, Patent Document 1).

In setting the reference value, the rated voltage is considered to have a margin for fluctuations in the power supply voltage. That is, the margin is set to a value such that the power supply voltage does not fall below the reference value due to a power supply voltage fluctuation assumed under normal use conditions or a voltage drop due to the impedance of the power supply cable. If the power supply voltage is equal to or higher than the reference value, the image forming apparatus is designed to operate normally.
JP-A-6-35562

  The power supply situation varies depending on the area and location where the image forming apparatus is installed and the usage environment of the user. For this reason, in an environment where the impedance of the power supply is high and the voltage drop is large, or the power supply is shared with other devices, the power supply voltage may drop below the reference value.

  When a voltage drop is detected during printing, the image forming apparatus immediately suspends the printing operation, and when returning to the initial state, the paper being printed stays in the apparatus and jams. In fact, in many cases, a voltage drop is detected during printing. This is because the rate at which heat is supplied to the fixing device is high during warm-up or printing. Once a jam has occurred, in order to resume the printing process, the user needs to remove the paper in the machine that is causing the paper jam and restart the printing process from the beginning, which bothers the user. Further, when the apparatus is initialized by detecting the power supply voltage drop, the contents of the job set by the user on the operation panel or the like are initialized, so that resetting is necessary. Therefore, it is preferable to control the image forming apparatus so as to avoid a power supply voltage drop.

  There is a demand for an image forming apparatus that can continue a printing operation or a warm-up operation without interrupting or initializing the operation of the apparatus when the power supply voltage at the power input section drops.

  According to the present invention, an image formation control unit that controls power consumption during operation related to image formation, a power setting unit that presets an upper limit value and a lower limit value of the power consumption, and an external input via a power wiring. A power supply voltage detection unit that detects a power supply voltage with a voltage drop caused by a power supply current flowing through the power wiring during operation related to the image formation, and the image formation control unit, An image forming apparatus is provided, wherein the power consumption is controlled within a range between the upper limit value and the lower limit value so that the power supply voltage is maintained at a predetermined voltage or higher.

  Here, the image forming apparatus is an apparatus that receives image data and prints it on a recording medium. For example, the image forming apparatus includes a printer, a copier, a facsimile, or a complex machine that combines them. The operation related to image formation does not simply indicate an operation during the printing process, but includes, for example, an initialization operation after turning on the power, an operation during warm-up, and a preparation operation necessary for image formation. Also includes post-processing operations after printing. The power supply current and the power supply voltage may indicate the effective value of the current or voltage. However, the power supply current and the power supply voltage are not limited to the execution value, and may be, for example, an instantaneous maximum value or another index correlated with the effective value. There may be. The index may be selected as appropriate by the apparatus designer in accordance with the characteristics of the apparatus. Further, the upper limit value and the lower limit value may be set by a service engineer or a user according to the environment in which the image forming apparatus is installed.

  The voltage drop of the power supply is caused by the internal impedance of the AC power supply when the power supply system side is viewed from the image forming apparatus. This occurs when the power wiring has an impedance component. The impedance component includes a wiring resistance of the power wiring.

  In the image forming apparatus according to the present invention, the image forming control unit controls the power consumption within the range between the upper limit value and the lower limit value so as to keep the power supply voltage at a predetermined voltage or higher. Then, the image formation control unit suppresses power consumption to reduce the power supply current, and thus tries to reduce the voltage drop. On the other hand, when the power supply voltage is sufficiently higher than the predetermined voltage, the power consumption is increased, and control is performed so that image formation is performed in a short time by supplying sufficient power. As a result, optimal power is supplied to the image forming apparatus so as to perform image formation in a short time while avoiding interruption of the image forming operation or initialization of the apparatus due to a voltage drop. In other words, since the power consumption is controlled according to the installation environment of the image forming apparatus, it is possible to avoid a situation in which the power supply voltage drops below the predetermined voltage and printing is interrupted or JAM occurs frequently. Therefore, the user is not bothered to restore the generated JAM or reset the print processing. The present invention is particularly effective when the image forming apparatus is used under conditions where power supply conditions are poor.

  A power consumption acquisition unit that acquires the power consumption based on a measurement result of the power supply current input to the image forming apparatus and the power supply voltage may be further provided. In this way, it is possible to accurately acquire the power consumption of the image forming apparatus based on the measurement result of the power supply voltage and the power supply current, and the image formation control unit can control the power consumption by accurately changing the power consumption.

  Further, the image formation control unit controls power consumption during operation related to electrophotographic image formation, and supplies the power consumption to the fixing unit in order to keep the power consumption within the range between the upper limit value and the lower limit value. You may control to change electric power. In this case, the image formation control unit controls the power supply so that the print job is completed in as short a time as possible while keeping the power consumption within the range between the upper limit value and the lower limit value. can do.

  Alternatively, a power consumption acquisition unit that acquires the power consumption by estimating the power consumption based on control information of the fixing unit may be further provided. Here, the control signal is, for example, an on / off signal for energizing the fixing unit, and the power acquisition unit estimates power consumption of the fixing unit from the on-time within a predetermined period, and other than the fixing unit. An estimated value of power consumption may be added to estimate the power consumption of the entire image forming apparatus. Since most of the power consumption of the image forming apparatus is the power consumption of the fixing unit, if the power of the fixing unit can be estimated accurately, the estimation of the total power consumption is valid. Alternatively, the control signal may be a phase control signal for controlling energization to the fixing unit. In this way, power consumption can be acquired without using a complicated measuring unit.

  The image formation control unit may control an operation so as to change a printing speed according to the control of the power consumption. In this way, it is possible to avoid the occurrence of fixing failure by setting the printing speed to match the power supplied to the fixing unit.

  Alternatively, the image formation control unit may control the operation so as to change the paper feed interval of the printing paper in accordance with the control of the power consumption. In this way, it is possible to avoid the occurrence of fixing failure by intermittently feeding the printing paper according to the power supplied to the fixing unit.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. The following description will provide a better understanding of the present invention. In addition, the following description is an illustration in all points, Comprising: It should be thought that it is not restrictive.

<Mechanical configuration of image forming apparatus>
FIG. 2 is an explanatory diagram showing an example of a mechanical configuration of the image forming apparatus according to the present invention. In FIG. 2, the image forming apparatus 71 records and outputs an image read by the image reading apparatus and data from a device (for example, an image processing apparatus such as a personal computer) connected to the image forming apparatus 71 from the outside. This is an electrophotographic printer.

  In the image forming apparatus 71, each process unit responsible for each function of the image forming process is arranged around the photosensitive drum 202, and an image forming unit is formed by these. Around the photosensitive drum 202, a charging unit 203, a developing unit 200 as a developing unit, a transfer roller 207, a cleaning unit 208, an optical scanning unit 204, and the like are arranged in this order.

  The charging unit 203 uniformly charges the surface of the photosensitive drum 202. The optical scanning unit 204 scans an optical image on the uniformly charged photosensitive drum 202 and writes an electrostatic latent image. The developing unit 200 visualizes the electrostatic latent image written by the optical scanning unit 204 with a developer supplied from the developing unit 200. Further, the developing unit 200 is provided with a toner container 72 for supplying toner to the unit. The transfer roller 207 functions as a transfer unit that transfers an image visualized on the photosensitive drum 202 onto a sheet of recording material and forms a visible image on the sheet. The cleaning unit 208 removes the developer remaining on the photosensitive drum 202 and makes it possible to record a new image on the photosensitive drum 202.

  Below the image forming apparatus 71, a supply tray 201 that is housed in the main body of the image forming apparatus 71 is disposed. The supply tray 201 is a recording material storage tray that stores recording material (paper). The sheets stored in the supply tray 201 are separated one by one at a predetermined time interval by the pickup roller 209 and the like, conveyed to the registration roller 210, and synchronized with the image formed on the photosensitive drum 202 by the registration roller 210. Is peeled off and supplied sequentially between the transfer roller 207 and the photosensitive drum 202. The image recorded and reproduced on the photosensitive drum 202 is transferred onto the sheet by the action of electrostatic force acting on the toner charged by the transfer voltage applied to the transfer roller 207. The supply of paper to the supply tray 201 is performed by pulling out the supply tray 201 to the front side (operation side) of the image forming apparatus 71.

In FIG. 2, three sheets S1, S2, and S3 are conveyed at predetermined intervals in the image forming apparatus 71. The paper transport timing is controlled by a control board 30 described later.
A fixing device 205 is disposed in the upper part of the image forming apparatus 71. The fixing device 205 sequentially receives the paper on which the image has been transferred, and fixes the developed image transferred on the paper by heat and pressure by the fixing roller 211, the pressure roller 212, and the like.

  The sheet on which the image is recorded is further conveyed upward. Then, it is discharged to a stacking tray 70 provided in the exterior of the image forming apparatus 71. When double-sided image formation or post-processing is specified, the paper is discharged toward the stacking tray 70, but the reverse roller 213 is reversed with the reverse edge of the paper held between the reverse rollers 213. Then, the paper is reversed and conveyed in the reverse direction, that is, in the direction of the conveyance path provided for double-sided image formation and post-processing.

  The control board 30 is a circuit board for controlling the operation of each part related to the image formation described above. An input / output circuit for inputting a signal from each sensor and outputting a signal for addition to the control board 30, a communication circuit for exchanging with a host computer (not shown), and controlling each input signal and communication A microcomputer 11, a ROM that stores a procedure of processing executed by the microcomputer 11, a RAM that provides a work area for the microcomputer to process images and data, and a nonvolatile memory element that holds data are mounted. .

  Control for detecting power supply voltage and changing power consumption is executed mainly by the microcomputer 11 of the control board 30 in FIG. 2 and a control program stored in a ROM (not shown). In other words, the image formation control unit that controls the operation related to image formation is realized by the microcomputer 11 executing processing according to the control program and performing control based on the state of each input signal.

<Electrical configuration>
FIG. 1 is a block diagram illustrating an example of an electrical configuration of the image forming apparatus 71. In FIG. 1, the AC power supply voltage from the AC power supply input terminal 1 is input to the DC power supply circuit 7 and the fixing power control circuit 15 through the power consumption measuring circuit 19 and further input to the AC voltage detection circuit 5. The DC power supply voltage output from the DC power supply circuit 7 is supplied to the image forming unit 23 and the control board 30. The image forming unit 23 is a block that performs operations related to image formation. The charging unit 203 of the image forming apparatus 71, the optical scanning unit 204, the transfer roller 207, the pickup roller 209, the registration roller 210, etc. Or a plurality of paper detection sensors arranged in the paper conveyance paths S1 to S3 to detect the paper passing through the paper conveyance path, and sensors arranged in the image forming apparatus 71. Further, the control board 30 determines the power supply voltage detected by the AC voltage detection circuit 5, the power consumption of the image forming apparatus 71 detected by the power consumption measurement circuit 19, and the state of each sensor of the detected image forming unit 23, Each load of the image forming unit 23 is driven, and a control signal is output to the fixing voltage control circuit 15 that controls the power supplied to the fixing heater lamp 17. Further, the control unit 21 controls the operation panel 21 for notifying the user of the state of the image forming apparatus 71 and inputting an instruction relating to image formation.

  The power consumption measurement circuit 19 as a power consumption acquisition unit is a circuit arranged at a portion where an AC voltage is input to the image forming apparatus 71 via the AC power input terminal 1 and measures a power supply voltage and a current. The power consumption of the image forming apparatus 71 is measured. Since the power consumption of the image forming apparatus 71 can be obtained by other methods, the power consumption measuring circuit 19 is not an essential component of the present invention. The power consumption measuring circuit 19 can be realized by applying a known circuit used in a power measuring device or the like. More specifically, the current detection circuit using electromagnetic induction, the voltage detection circuit, the power supply current waveform detected by the current detection circuit, and the power supply voltage waveform detected by the voltage detection circuit are considered in consideration of the power factor. It is comprised with the calculation part which calculates electric power.

  The AC voltage detection circuit 5 as a power supply voltage detection unit is a block that detects an AC power supply voltage. The detection result of the AC voltage detection circuit 5 is provided to the control board 30 so that the microcomputer 11 can determine the voltage drop state of the AC power supply. The AC voltage detection circuit 5 can be realized by applying a known circuit used in a voltmeter or the like. When the voltage of the AC power supply falls below a predetermined threshold value, the microcomputer 11 interrupts the operation related to image formation of the image forming apparatus 71 in order to avoid the runaway of the microcomputer 11 and applies a load. In addition to blocking, the counter and the data to be saved are saved.

  The fixing power control circuit 15 is a circuit for controlling the power supplied to the fixing device 205 in accordance with the control of the microcomputer 11. A fixing heater lamp 17 is provided inside the fixing roller 211 of the fixing device 205 to overheat the fixing roller 211 and keep the surface of the roller at a predetermined temperature. The fixing power control circuit 15 includes a fixing heater lamp 15. The phase of the AC voltage supplied to 17 is controlled to control the power supplied when energized, and when the surface of the fixing roller 211 reaches a predetermined temperature or higher, the AC voltage supply to the fixing heater lamp 17 is cut off to fix the fixing roller 211. The surface of 211 is controlled to be a predetermined temperature. The fixing power control circuit 15 can be composed of, for example, a power switching element such as a triac or thyristor and a known control circuit for controlling on / off of the switching element. In this embodiment, it is assumed that the fixing heater lamp 17 is phase-controlled by a power switching element so that the supplied power can be continuously changed. However, the control method of the fixing heater lamp 17 is not limited to the phase control, and any method can be used as long as the supplied power can be changed in a plurality of stages. For example, the average power may be controlled by controlling on / off for each half wave of the power waveform, or the AC power may be converted into direct current and driven by an inverter circuit.

  In addition, the control board 30 can exchange signals with the operation panel 21, display the status of the image forming apparatus 71 and control information, and allow the user to input various settings and instructions related to image formation. The microcomputer 11 can cause the user to set in advance the upper limit value and the lower limit value of the power consumption of the image forming apparatus 71 during operation related to image formation via the operation panel 21. The function as the power setting unit is that the microcomputer 11 executes a control program stored in a ROM (not shown) of the operation board 30 and sets an upper limit value and a lower limit value of power consumption to the user using the operation panel 21. It is realized by letting.

  Here, the upper limit value of the power consumption is set in consideration of the current capacity of the power source. The rating of the power capacity depends on the breaking characteristics of the safety breaker provided in the power source. The safety breaker breaking characteristics are designed to satisfy the standards defined in the Electrical Appliance and Material Safety Law in Japan. For example, a typical 15V rated characteristic for 110V does not operate automatically when a current of 17.2A is passed until the temperature rise of the breaker becomes almost constant, but when a current of 22.5A is passed. It does not operate within 30 seconds, operates within 60 seconds, does not operate within 1 second, and operates within 30 seconds when a 55 A current is passed through. The upper limit value of the power consumption is set so that the upper limit of the power consumption of the image forming apparatus 71 is within the range of the breaking characteristics of the breaker.

<Control of power consumption based on detection of power supply voltage>
(Embodiment 1)
FIG. 3 shows an example of how the microcomputer 11 of FIG. 1 controls the fixing power based on the information of the power supply voltage detected by the AC voltage detection circuit 5, thereby controlling the power consumption of the image forming apparatus. It is a time chart. The vertical axis of FIG. 3A is the value of the power supply voltage grasped by the microcomputer 11 based on the detection of the AC voltage detection circuit, and the horizontal axis is time. V _reset is detected by a protection circuit in the control board 30 when the power supply voltage drops below the level, and the microcomputer 11 performs a protection operation including a suspension process and an interruption of the image forming process in order to avoid a runaway. Threshold voltage to be applied. Also, the vertical axis of FIG. 3B represents the power consumption measuring circuit 19 of FIG. 1 or an image forming apparatus grasped by an alternative means for estimating power consumption in an image forming apparatus that does not include the power consumption measuring circuit 19. The horizontal axis is time. Here, the AC power supply voltage detected by the AC voltage detection circuit 5 is an effective value for a period longer than the switching period by the power switching element, and preferably an effective value for a period of 5 to 6 periods. Therefore, it does not give an instantaneous value of the voltage waveform, but detects a change in voltage with a delay of several cycles.

In FIG. 3, the image forming apparatus is in a standby state until time T ₁ , and its power consumption is P ₀ . During standby, there are few operating parts of the apparatus, and the heat of the fixing unit is not taken away by the passage of printing paper, so the power consumption is less than during image formation. At time T ₁ , in response to a request for image formation, an operation related to image formation is started. The microcomputer 11 determines the power to be supplied to the fixing heater lamp 17 so that the power consumption of the image forming apparatus is close to a predetermined lower limit value P _min but does not fall below P _min. A control signal is output to the fixing power control circuit 15 so as to supply. The power to be supplied to the fixing heater lamp 17 in order to set the power consumption of the image forming apparatus to a target value is stored in advance as a standard power consumption characteristic of the image forming apparatus as a database, and is based on the stored database. To decide. In the case where the phase of the fixing heater lamp 17 is controlled by way of example, the database is provided as a data table that gives the phase angle to be controlled from the target power consumption and the power supply voltage detected by the AC voltage detection circuit 5. .

As shown in FIG. 3, as a result of controlling the power supplied to the fixing heater lamp 17 based on the database, the power consumption of the image forming apparatus becomes P ₁ , and the power consumption increases from P ₀ to P ₁ . Accordingly, the power supply voltage drops from V ₀ to V ₁ . The AC voltage detection circuit 5 detects that the power supply voltage has dropped to V ₁ . Although there is a voltage drop from V ₀ to V ₁ , it is sufficiently larger than the threshold voltage V _reset of the protection operation described above, so the microcomputer 11 further supplies power to the fixing heater lamp 17 at time T ₂ . increase. As a result, the power consumption of the image forming apparatus is P ₂ and the power supply voltage is V ₂ .

Since the power supply voltage V ₂ still has room for V _reset , the microcomputer 11 further increases the power supplied to the fixing heater lamp 17 by one step at time T ₃ . As a result, the power consumption of the image forming apparatus is P ₃ and the power supply voltage is V ₃ .
Since the power supply voltage V ₃ still has room for V _reset , the microcomputer 11 further increases the power supplied to the fixing heater lamp 17 by one step at time T ₄ . As a result, the power consumption of the image forming apparatus becomes P ₄ close to the upper limit value P _max and the power supply voltage becomes V ₄ .

Although the power supply voltage V ₃ still has room for V _reset , the power consumption of the image forming apparatus is close to the upper limit value P _max , so that the microcomputer 11 uses the power supplied to the fixing heater lamp 17 for the image forming operation. to maintain until the time T ₅ to end.
Immediately after the start of the image forming operation, the power consumption for fixing is small, but the printing paper is sufficiently fixed by the amount of heat stored in the fixing unit during standby. The control for switching the power supplied to the fixing unit stepwise is terminated before the heat amount of the fixing unit is taken by the printing paper and a fixing failure occurs.
The above example is an example of power control when the power source is stable and the voltage drop is small.

(Embodiment 2)
Next, an example in which the voltage drop of the power supply is large will be described.
FIG. 4 shows a different example in which the microcomputer 11 in FIG. 1 controls the fixing power based on the information of the power supply voltage detected by the AC voltage detection circuit 5 and thereby controls the power consumption of the image forming apparatus. It is a time chart which shows.

In FIG. 4, the image forming apparatus is in a standby state until time T ₁₁ , and its power consumption is P ₁₀ . At time T _10, the result of operation according a request is received image formed in the image formation is started, the power consumption of the image forming apparatus becomes P _11, with a P ₁₀ of the power consumption increase to P ₁₁ supply voltage drops from V ₁₀ to V _11. AC voltage detection circuit 5 detects that the power supply voltage drops to V _11. Although there is a voltage drop from V ₁₀ to V ₁₁ , it is sufficiently larger than the threshold voltage V _reset of the protective operation described above, so that the microcomputer 11 further increases the power supplied to the fixing heater lamp 17 at time T ₁₂ . increase. As a result, the power consumption of the image forming apparatus is P ₁₂ and the power supply voltage is V ₁₂ .

Since the power supply voltage V ₁₂ still has room for V _reset , the microcomputer 11 further increases the power supplied to the fixing heater lamp 17 by one step at time T ₁₃ . As a result, the power consumption of the image forming apparatus is P ₁₃ and the power supply voltage is V ₁₃ .
The power supply voltage V ₁₃ still does not have a sufficient margin for V _reset . Therefore, the microcomputer 11 reduces one step power supplied to the fusing heater lamp 17 at time T _14. Power consumption of the image forming apparatus becomes P _14, the power source voltage becomes V _14. The microcomputer 11 maintains the power supplied to the fusing heater lamp 17 to the time T ₁₅ of the image forming operation is completed.
The above example is an example of power control when the voltage drop is large.

(Embodiment 3)
In the first and second embodiments, the control in which the microcomputer 11 switches the power supplied to the fixing heater lamp 17 stepwise has been described. However, if the voltage drop is caused by the wiring resistance, the voltage drop is proportional to the power supply current. Since the apparatus having the power consumption measurement circuit 19 as shown in FIG. 1 measures the power supply current for power measurement, it is possible to obtain information on the power supply current. Therefore, for example, if the microcomputer 11 grasps the increase in the power supply current when the image forming operation is started from the standby state and grasps the drop in the power supply voltage with the AC voltage detection circuit 5, the increase in the power supply current and the power supply voltage are detected. The power supply current that gives the target value of the power supply voltage with a margin with respect to the power supply voltage V _reset can be estimated from the relationship between the power supply voltage V _reset and the power consumption corresponding to the estimated power supply current and the target power supply voltage Can be guessed. The power supplied to the fixing heater lamp 17 corresponding to the estimated power consumption can be determined based on the database described above.

  In FIG. 5, the microcomputer 11 shown in FIG. 1 controls the fixing power based on the information about the power supply current acquired from the power consumption measuring circuit 19 and the power supply voltage detected by the AC voltage detection circuit 5, whereby the image is displayed. It is a time chart which shows another example of a mode that the power consumption of a forming apparatus is controlled.

In FIG. 5, the image forming apparatus is in a standby state until time T ₂₁ , and its power consumption is P ₂₀ . The power supply current at this time is I ₂₀ . As a result of the start of the operation related to image formation in response to the request for image formation at time T ₂₀ , the power consumption of the image forming apparatus becomes P ₂₁ , and the power consumption increases from P ₂₀ to P ₂₁ . supply voltage drops from V ₂₀ to V _21. Power current when the power consumption P ₂₁ and I _21. At this time, the power consumption measuring circuit 19 detects that the power consumption is P ₂₁ and the power source current is changed from I ₂₀ to I ₂₁ . Further, AC voltage detection circuit 5 detects that the power supply voltage drops to V _11. The microcomputer 11, the determined power supplied from the drop of the change and the power supply voltage of the power supply current to the fixing heater lamp 17, switches the power supply at time T _22.

FIG. 6 is a graph showing the relationship between the power supply current detected by the power consumption measurement circuit 19 and the power supply voltage detected by the AC voltage detection circuit 5 in this embodiment. As described above, the power source current is I ₂₀ and the power source voltage is V ₂₀ until time T _{21. In} FIG. 6, this state is indicated by S 20. Time T ₂₁ later, the power source current I _21, the power supply voltage becomes V _21. This point is indicated by S21. S20 and S21 and the knot in a straight line, the point which gave a predetermined margin with respect to the threshold V _reset power supply voltage in this straight line and S _target. Supply voltage V _target giving S _target, a power supply current I _target, obtains the power consumption P _target from a pre-determined power factor, based on the power supplied to the fusing heater lamp 17 corresponding to the power consumption P _target in the aforementioned database Can be determined. As this way give power P _target estimated by the microcomputer 11 at time T _23, controls the power supplied to the fusing heater lamp 17. As a result, the actual power supply current becomes I ₂₂ and the power supply voltage becomes V ₂₂ . This corresponds to the operating point S ₂₂ in FIG.

Supply voltage V ₂₂ that is detected, because less than the target value of the aforementioned power supply voltage, the microcomputer 11 slightly increases the power supplied to the fusing heater lamp 17 at time T _23. As a result, power consumption of the image forming apparatus becomes P _23, the power source voltage becomes V _23. This corresponds to the operating point S ₂₃ in FIG.

Supply voltage V _23, so there is enough room for the V _reset, the microcomputer 11 maintains a supply power the power supplied to the fusing heater lamp 17 to the time T ₂₅ of the image forming operation is completed.
As described above, by obtaining the power supplied to the fixing heater lamp 17 from the change in the power supply current and the voltage drop, the power supplied to the fixing heater lamp 17 can be optimized in a shorter time than the methods of the first and second embodiments. Can be switched to a value.

  Finally, it is apparent that there can be various modifications of the present invention in addition to the above-described embodiment. Such variations are not to be construed as not belonging to the features and scope of the invention. The scope of the present invention is intended to include all modifications within the meaning and range equivalent to the scope of the claims.

1 is a block diagram illustrating an example of an electrical configuration of an image forming apparatus according to the present invention. It is explanatory drawing which shows an example of the mechanical structure of the image forming apparatus of this invention. 2 is a time chart showing an example of a state in which the microcomputer 11 in FIG. 1 controls fixing power based on power supply voltage information and thereby controls power consumption of the image forming apparatus. (Embodiment 1) 3 is a time chart showing a different example of how the microcomputer 11 in FIG. 1 controls the fixing power based on the power supply voltage information and thereby controls the power consumption of the image forming apparatus. (Embodiment 2) 3 is a time chart showing another example of how the microcomputer 11 in FIG. 1 controls the fixing power based on the information of the power supply voltage and thereby controls the power consumption of the image forming apparatus. (Embodiment 3) 4 is a graph showing a relationship between a power supply current detected by a power consumption measurement circuit 19 and a power supply voltage detected by an AC voltage detection circuit 5 in this embodiment. (Embodiment 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply input terminal 5 AC power supply voltage detection circuit 7 DC power supply circuit 11 Microcomputer 15 Fixing power control circuit 17 Fixing heater lamp 19 Power consumption measuring circuit 21 Operation panel 23 Image formation part 30 Control board 50 Toner supply path 53, 79 Toner Bottle positioning unit 54 Toner bottle 60 Developing roller 70 Loading tray 71 Image forming apparatus 72 Toner storage unit 200 Developing tank, developing unit 201 Supply tray 202 Photosensitive drum 203 Charging means 204 Optical scanning unit 205 Fixing device 207 Transfer roller 208 Cleaning unit 209 Pickup roller 210 Registration roller 211 Fixing roller 212 Pressure roller 213 Reverse roller

Claims (6)

An image formation control unit for controlling power consumption during operation related to image formation;
A power setting unit for presetting an upper limit value and a lower limit value of the power consumption;
A power supply voltage detection unit that detects a power supply voltage that is input from the outside through a power wiring and includes a voltage drop caused by a power supply current flowing through the power wiring during the operation related to the image formation; Prepared,
The image forming apparatus, wherein the image forming control unit controls the power consumption within a range between the upper limit value and the lower limit value so as to keep the power supply voltage at a predetermined voltage or higher.   The image forming apparatus according to claim 1, further comprising a power consumption acquisition unit that acquires the power consumption based on a measurement result of a power supply current input to the image forming apparatus and the power supply voltage.   The image formation control unit controls power consumption during operation related to electrophotographic image formation, and changes power supplied to the fixing unit in order to keep the power consumption within the range between the upper limit value and the lower limit value. The image forming apparatus according to claim 1, which is controlled as described above.   The image forming apparatus according to claim 3, further comprising a power consumption acquisition unit that acquires the power consumption by estimating the power consumption based on control information of the fixing unit.   The image forming apparatus according to claim 1, wherein the image forming control unit controls an operation so as to change a printing speed in accordance with the control of the power consumption.   The image forming apparatus according to claim 1, wherein the image forming control unit controls an operation so as to change a paper feed interval of the printing paper according to the control of the power consumption.

Images