JP6596916B2 - Fixing heater control method - Google Patents

Description

  The present invention relates to a fixing heater control method.

  In recent years, an image forming apparatus used for outputting digitized information has become an indispensable device. Among such image forming apparatuses, an image forming apparatus using an electrophotographic method is known.

  When an image is formed on a sheet, the electrophotographic image forming apparatus fixes the toner image on the sheet by heating the sheet onto which the toner image has been transferred with a fixing roller. For this reason, the electrophotographic image forming apparatus performs warm-up to supply power to the fixing heater until the fixing roller reaches a temperature at which fixing can be performed before image formation.

  However, in an electrophotographic image forming apparatus, when power supply to the fixing heater is started during warm-up, the power supply voltage may drop due to an inrush current. In an electrophotographic image forming apparatus, if the power supply voltage drops during warm-up, it takes longer to reach the temperature at which the fixing roller can be fixed, or the fixing roller is not heated to a temperature at which it can be fixed. Various problems may occur, such as a failure occurring or an operation being stopped due to an abnormality occurrence.

  Therefore, in order to prevent a voltage drop caused by an inrush current that flows during warm-up, the voltage value of the input voltage of an AC (Alternating Current) power supply is measured, and energization control to the fixing heater is performed according to the voltage value. Has been proposed and is already known (see, for example, Patent Document 1).

  However, in the conventional image forming apparatus as described in Patent Document 1, when there is a problem in the state of the AC power source such as a situation where the voltage of the AC power source is not stable, or when power is supplied through the saddle wiring, When power supply conditions are bad, such as when power is supplied via a long cable such as a reel cable, even if the energization control to the fixing heater is performed during warm-up, the inrush current flows and the allowable range is reached. The power supply voltage may drop beyond this value. In the electrophotographic image forming apparatus, when the power supply voltage drops beyond an allowable range, the above-described various problems occur.

  Further, the conventional image forming apparatus described in Patent Document 1 performs control for preventing a voltage drop caused by an inrush current that flows when power supply from the power source to the fixing heater is started during warm-up. Only measures are taken and no measures are taken to prevent voltage drops during the printing operation. For this reason, in the conventional image forming apparatus, when a voltage drop occurs during the printing operation, the above various problems occur even during the printing operation.

  The present invention has been made in view of the above circumstances, and an object thereof is to avoid a problem caused by a drop in power supply voltage that occurs when power is supplied to a fixing heater.

In order to solve the above problems, one aspect of the present invention is a fixing heater control method for controlling power supply to a fixing heater in an electrophotographic image forming apparatus, wherein the fixing heater is warmed up. by measuring the voltage drop of the power supply voltage due to an inrush current at power supply conductive Chikarakyo supply inrush current than when is controlled so Naru rather small to the fixing heater during the normal operation of the image forming apparatus, During the printing operation by the image forming apparatus, power supply to the fixing heater is controlled according to the voltage drop amount.

  According to the present invention, it is possible to avoid a problem caused by a drop in power supply voltage that occurs when power is supplied to the fixing heater.

1 is a diagram for explaining an overview of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention from a main scanning direction. 1 is a block diagram schematically illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram schematically illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows typically the functional structure of the voltage measurement part which concerns on embodiment of this invention. It is a figure which shows an example of the ON duty ratio determination table which concerns on embodiment of this invention. 6 is a flowchart for explaining ON duty ratio determination processing by the image forming apparatus according to the embodiment of the present invention; 1 is a diagram for explaining an overview of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram for explaining an overview of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows an example of the limitation number determination table which concerns on embodiment of this invention. 6 is a flowchart for explaining limit number determination processing by the image forming apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present exemplary embodiment, an image forming apparatus using an electrophotographic method among image forming apparatuses used for outputting digitized information will be described as an example.

  First, an outline of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram for explaining an overview of an image forming apparatus 1 according to the present embodiment. In FIG. 1, b> a.

  In an electrophotographic image forming apparatus, normally, when an image is formed on a sheet, the toner image is fixed on the sheet by heating the sheet onto which the toner image has been transferred with a fixing roller. For this reason, the electrophotographic image forming apparatus performs warm-up to supply power to the fixing heater until the fixing roller reaches a temperature at which fixing can be performed before image formation.

  However, in an electrophotographic image forming apparatus, when power supply to the fixing heater is started during warm-up, the power supply voltage may drop due to an inrush current.

  In particular, when there is a problem with the state of the AC power supply, such as when the voltage of the AC power supply is not stable, or when power is supplied via a saddle wire, when power is supplied via a long wire such as a reel cable When the power supply situation is bad, the power supply voltage may drop beyond the allowable range due to the inrush current flowing.

  In the electrophotographic image forming apparatus, if the power supply voltage drops during warm-up, it takes a long time for the fixing heater to reach a fixing temperature, or the fixing heater cannot be heated to a fixing temperature. For this reason, various problems may occur, such as a fixing failure, or an operation that is determined to be abnormal.

  Therefore, as shown in FIG. 1A, the image forming apparatus 1 according to the present embodiment first warms up in a state where the ON duty ratio of the fixing heater is lower than the ON duty ratio during normal operation and the inrush current is reduced. Up and measure the voltage drop of the power supply at that time. Then, the image forming apparatus 1 according to the present embodiment determines the ON duty ratio according to the measured voltage drop amount, and thereafter performs the printing operation by controlling the heating of the fixing heater at the determined ON duty ratio. It is configured.

  That is, as shown in FIG. 1B, the image forming apparatus 1 according to the present embodiment has an ON duty ratio when the measured voltage drop amount is not less than a predetermined value a (V) and less than b (V). In a state where the temperature is lower than the ON duty ratio during normal operation, the fixing heater is heated and controlled to perform a printing operation. This is because when the voltage drop amount is not less than a predetermined value a (V) and less than b (V), the heating control based on the ON duty ratio during normal operation does not reach the temperature at which the fixing roller can be fixed, or the fixing heater This is because it takes a long time to reach a fixing temperature.

  Therefore, even in such a case, the image forming apparatus 1 according to the present embodiment has the above problem that occurs due to a voltage drop by controlling the heating of the fixing heater to be lower than the ON duty ratio during normal operation. It can be avoided.

  Further, as shown in FIG. 1C, the image forming apparatus 1 according to the present embodiment has an ON duty ratio during normal operation when the measured voltage drop amount is less than a predetermined value a (V). The printing operation is performed by controlling the heating of the fixing heater. This is because when the voltage drop amount is less than the predetermined value a (V), the time until the fixing roller reaches a temperature at which the fixing roller can be fixed does not become long even with the heating control by the ON duty ratio in the normal operation.

  Accordingly, in such a case, the image forming apparatus 1 according to the present embodiment shortens the time until the fixing roller reaches a temperature at which the fixing roller can be fixed by controlling the heating of the fixing heater at the ON duty ratio during normal operation. It becomes possible. Thereby, the image forming apparatus 1 according to the present embodiment can improve productivity.

  In addition, as shown in FIG. 1D, the image forming apparatus 1 according to the present embodiment, when the measured voltage drop amount is equal to or greater than a predetermined value b (V), thereafter power to the fixing heater. Stop supplying. This is because even if the heating control is performed below the ON duty ratio during normal operation, the fixing roller does not reach the temperature at which fixing can be performed.

  Therefore, the image forming apparatus 1 according to the present embodiment can avoid performing a printing operation in an abnormal state in which the fixing roller cannot reach a temperature at which fixing can be performed, and a fixing failure occurs, It is possible to avoid the problem that the operation stops during the printing operation.

  Here, when the image forming apparatus 1 according to the present embodiment warms up, the ON duty ratio is lowered below the ON duty ratio during normal operation to reduce the inrush current, and the power supply at that time is The reason for measuring the voltage drop will be described.

  When the image forming apparatus warms up with the ON duty ratio lower than that during normal operation, it is unclear whether the power supply voltage drops due to an inrush current even if the power supply voltage drops by a predetermined value b (V) or more. Therefore, it is unclear whether the voltage drop will improve even if the ON duty ratio is lowered. For this reason, the image forming apparatus may not operate normally even if a printing operation is performed with the ON duty ratio being lower than the ON duty ratio during normal operation in such a state.

  Therefore, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the ON duty ratio is lower than the ON duty ratio during normal operation, and measures the voltage drop amount at that time, thereby determining the ON duty ratio. It becomes possible to grasp in advance whether or not the voltage drop is improved by lowering.

  That is, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the ON duty ratio is lower than the ON duty ratio during normal operation, and the voltage drop amount at that time is a predetermined value a (V) or more b If it is less than (V), it is possible to know that the printing operation can be normally performed by lowering the ON duty ratio before entering the printing operation.

  Further, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the ON duty ratio is lower than the ON duty ratio during normal operation, and the voltage drop amount at that time is less than a predetermined value a (V). In some cases, it is possible to know that the printing operation can be normally performed without lowering the ON duty ratio before entering the printing operation.

  Further, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the ON duty ratio is lower than the ON duty ratio during normal operation, and the voltage drop amount at that time is equal to or greater than a predetermined value b (V). In some cases, it is possible to know before starting the printing operation that the printing operation cannot be performed normally.

  Note that the image forming apparatus performs a process of determining the ON duty ratio by measuring the amount of voltage drop of the power supply every time during warm-up before entering the printing operation (hereinafter referred to as “ON duty ratio determination process”). As a result, the time from the start of the warm-up to the actual start of the printing operation becomes longer and the productivity is lowered.

  Therefore, the image forming apparatus 1 according to the present embodiment performs the ON duty ratio determination process only at the time of warm-up when the power is turned on, and at subsequent printing, the ON duty ratio determination process performed at the time of warm-up when the power is turned on. The fixing heater is heated and controlled according to the determined ON duty ratio to perform a printing operation. Here, the subsequent printing is, for example, printing excluding printing associated with power-on, such as printing when returning from a sleep state or an energy saving state, or printing from a standby state.

  That is, in the image forming apparatus 1 according to the present embodiment, when the voltage drop amount of the power supply measured at the time of warm-up when the power is turned on is greater than or equal to the predetermined value a (V) and less than b (V), In a state where the ON duty ratio is lower than the ON duty ratio during normal operation, the fixing heater is heated to perform a printing operation.

  Further, in the image forming apparatus 1 according to the present embodiment, when the amount of voltage drop measured during warm-up when the power is turned on is less than the predetermined value a (V), the ON duty ratio during normal operation is used during subsequent printing. Then, the fixing heater is heated and controlled to perform the printing operation.

  Further, in the image forming apparatus 1 according to the present embodiment, when the voltage drop amount measured at the time of warm-up when the power is turned on is equal to or larger than the predetermined value b (V), power is supplied to the fixing heater at the time of subsequent printing. Stop.

  Next, the overall configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing the image forming apparatus 1 according to the present embodiment from the main scanning direction.

  As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment has a configuration in which image forming units 129 of respective colors are arranged in series, and includes an image forming mechanism called a so-called tandem type. is there.

  In other words, the image forming apparatus 1 according to the present embodiment is configured from the upstream side in the transport direction of the transport belt 136 along the transport belt 136 spanned between the driving roller 137, the driven roller 138, and the secondary transfer roller 139a. A plurality of image forming units, a C plate image forming unit 129C, an M plate image forming unit 129M, a Y plate image forming unit 129Y, and a K plate image forming unit 129K are arranged in this order.

  The plurality of image forming units 129C, 129M, 129Y, and 129K have the same internal configuration except that the color of the toner image to be formed is different. The C plate image forming unit 129C forms a cyan image, the M plate image forming unit 129M forms a magenta image, the Y plate image forming unit 129Y forms a yellow image, and the K plate image forming unit 129K forms a black image. .

  The components of the image forming units 129M, 129Y, and 129K are the same as those of the C plate image forming unit 129C. Therefore, in the following description, the C plate image forming unit 129C will be described in detail, but each component of the other image forming units is replaced with C attached to each component of the C plate image forming unit 129C. Thus, only the symbols distinguished by M, Y, and K are displayed in the figure.

  The conveyor belt 136 is an endless belt, that is, an endless belt that is stretched around a driving roller 137, a driven roller 138, and a secondary transfer roller 139a that are rotationally driven. Further, the transport belt 136 is an intermediate transfer belt on which an intermediate transfer image is formed by each image forming unit, the C plate image forming unit 129C, the M plate image forming unit 129M, the Y plate image forming unit 129Y, and the K plate image forming unit 129K. It is.

  The drive roller 137 is driven to rotate by a drive motor. The drive motor, the drive roller 137, the driven roller 138, and the secondary transfer roller 139a move the transport belt 136.

  The C plate image forming unit 129C includes a photosensitive drum 130C as a photosensitive member, a charger 131C, a developing unit 132C, a charge eliminator 133C, a toner recovery unit, and the like disposed around the photosensitive drum 130C.

  The C plate image forming unit 129 </ b> C forms a cyan intermediate transfer image on the conveyor belt 136 during image formation. That is, when forming an image, the C plate image forming unit 129C first uniformly charges the outer peripheral surface of the photosensitive drum 130C with the charger 131C in the dark.

  Then, the C plate image forming unit 129C performs electrostatic writing by irradiating the uniformly charged photosensitive drum 130C with light corresponding to the cyan image from the optical writing device 134C, and the outer periphery of the photosensitive drum 130C. An electrostatic latent image is formed on the surface. The C-plate image forming unit 129C forms a cyan toner image on the outer peripheral surface of the photosensitive drum 130C by visualizing the electrostatic latent image with cyan toner by the developing device 132C.

  The C-plate image forming unit 129C presses the primary transfer roller 135C against the photosensitive drum 130C by a biasing member at a position where the photosensitive drum 130C and the conveying belt 136 are in contact with or closest to each other. The image is transferred onto the conveyance belt 136. By this transfer, an image of cyan toner, that is, a cyan intermediate transfer image is formed on the conveyance belt 136. Hereinafter, a position where the photosensitive drum 130 </ b> C and the conveyor belt 136 are in contact with or closest to each other is referred to as a “primary transfer position”.

  At this time, a transfer bias is applied to the primary transfer roller 135C, and a transfer electric field is formed between the photosensitive drum 130C and the primary transfer roller 135C at the preceding transfer position by the transfer bias. Then, the toner image is transferred from the photosensitive drum 130 </ b> C to the conveyance belt 136 by the action of the transfer electric field.

  When the C-plate image forming unit 129C finishes forming the cyan intermediate transfer image on the conveyance belt 136, the toner collecting unit collects the toner remaining on the outer peripheral surface of the photosensitive drum 130C, and then the outer periphery of the photosensitive drum 130C. The surface is neutralized by the neutralizer 133C. Then, the C-plate image forming unit 129C prepares for the next image formation and waits.

  The cyan intermediate transfer image transferred onto the conveyance belt 136 as described above is moved to the next M plate by the conveyance belt 136 being moved by the drive motor, the drive roller 137, the driven roller 138, and the secondary transfer roller 139b. It is conveyed to the image forming unit 129M.

  The M plate image forming unit 129M forms a magenta toner image on the photosensitive drum 130M by a process similar to the image forming process in the C plate image forming unit 129C. Then, the M plate image forming unit 129M transfers the magenta toner image onto the conveyance belt 136 while superimposing the magenta toner image on the already formed cyan intermediate transfer image. By this transfer, an image of magenta toner, that is, a magenta intermediate transfer image is formed on the conveyance belt 136.

  The cyan and magenta intermediate transfer images formed on the conveyor belt 136 are further sequentially conveyed to the next image forming unit, Y plate image forming unit 129Y, and K plate image forming unit 129K. By the same operation, the yellow toner image formed on the photosensitive drum 130Y and the black toner image formed on the photosensitive drum 130K are superimposed on the already formed intermediate transfer image. The image is transferred onto the conveyance belt 136.

  By this transfer, an image using yellow toner and an image using black toner, that is, an intermediate transfer image of yellow and black, are formed on the conveyance belt 136. Thus, a full-color intermediate transfer image is formed on the conveyance belt 136.

  When a full-color intermediate transfer image is formed on the conveyance belt 136 in this way, the separation roller 102 and the pair of sheet supply rollers 103, 104, 105 are arranged in order from the uppermost sheet S stored in the sheet supply tray 101. And are supplied separately. Then, the separately supplied sheet S is sent out toward the relay unit 106. The sheet supply trays 101a, 101b, and 101c store sheets of different sheet types such as sheet size, sheet thickness, and sheet material.

  The relay unit 106 to which the sheet S has been conveyed conveys the sheet S toward the nip portion of the resist roller pair 117 that is stopped in the registration unit 116 by the relay roller pair 107, whereby the secondary transfer roller pair 139. Correct the inclination of the seat with respect to. The relay unit 106 further conveys the sheet to the downstream side in the conveyance direction.

  Then, the registration unit 116 conveys the sheet S whose inclination is corrected by the registration roller pair 117 toward the nip portion of the secondary transfer roller pair 139, that is, the secondary transfer position in accordance with the conveyance timing of the conveyance belt 136. .

  The secondary transfer roller pair 139 is a full color formed on the transport belt 136 by sandwiching the sheet S and the transport belt 136 at the secondary transfer position by the secondary transfer roller 139a and the secondary transfer roller 139b at the same time. The intermediate transfer image is transferred to the sheet S. As a result, an image is formed on the sheet surface of the sheet S.

  At this time, the toner that adheres to the surface of the conveyor belt 136 by the cleaning blade pressed against the conveyor belt 136 downstream of the secondary transfer position in the conveyance direction and upstream of the C-plate image forming unit 129C. It is cleaned by scratching.

  The secondary transfer roller pair 139 conveys the sheet S on which the image is formed in this way toward the fixing unit 140. The fixing unit 140 fixes the image by sandwiching the sheet S between the fixing roller 140a and the fixing roller 140b from a direction perpendicular to the image forming surface and applying pressure while heating. The fixing unit 140 conveys the sheet S on which the image is fixed in this way toward the branch roller pair 141.

  At this time, the branching claw 142 switches the conveyance path to one of a discharge path for discharging the sheet S to the outside of the image forming apparatus 1 and a reverse path for reversing the front and back of the sheet S. Accordingly, the branch roller pair 141 conveys the sheet S on which the image is fixed toward the discharge roller pair 143 or conveys the sheet S toward the reverse path entrance roller pair 144.

  When the branching claw 142 is switched to the reverse path, the reverse path entrance roller pair 144 conveys the sheet S toward the forward / reverse rotating roller pair 145. Then, the forward / reverse rotating roller pair 145 reverses the front and back of the sheet S by reversing the rotation direction in anticipation of the reversal timing of the sheet S. In this way, the sheet S whose front and back sides are reversed is sent out toward the relay unit 106 by the pair of reverse rollers 146, 147, 148, and 149. Then, images are formed on both sides of the sheet S which is reversed and conveyed to the relay unit 106 by the same process.

  As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment is a system in which an intermediate transfer image is formed on a conveyance belt 136 and the intermediate transfer image is transferred to a sheet, that is, an indirect transfer system. This is an image forming apparatus. In addition, the image forming apparatus 1 according to the present embodiment may be a system in which an image is directly formed on a sheet, that is, a direct transfer type image forming apparatus.

  Next, a hardware configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 3 is a block diagram schematically illustrating a hardware configuration of the image forming apparatus 1 according to the present embodiment.

  As shown in FIG. 3, the image forming apparatus 1 according to the present embodiment includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 20, a ROM (Read Only Memory) 30, an HDD (Hard Disk Drive) 40, A dedicated device 50, an operation device 60, a display device 70, and a communication I / F 80 are connected via a bus 90.

  The CPU 10 is a calculation unit and controls the operation of the entire image forming apparatus 1. The RAM 20 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The ROM 30 is a read-only nonvolatile storage medium and stores a program such as firmware.

  The HDD 40 is a non-volatile storage medium capable of reading and writing information, and stores various data such as image data, various programs such as an OS (Operating System), various control programs, and application programs.

  The dedicated device 50 is hardware for realizing a dedicated function in the image forming apparatus 1. That is, the dedicated device 50 is hardware for realizing a dedicated function in a printer, a facsimile, a scanner, and a copying machine. As described above, the image forming apparatus 1 according to the present embodiment includes an imaging function, an image forming function, a communication function, and the like, so that it can be used as a printer, a facsimile, a scanner, a copying machine, or the like (multi function peripheral: MFP). ).

  The operation device 60 is a user interface for inputting information to the image forming apparatus 1 and is realized by an input device such as a keyboard, a mouse, an input button, or a touch panel.

  The display device 70 is a visual user interface for the user to check the state of the image forming apparatus 1 and is realized by a display device such as an LCD (Liquid Crystal Display) or an output device such as an LED (Light Emitting Diode). .

  The communication I / F 80 is an interface through which the image forming apparatus 1 communicates with other apparatuses, and includes Ethernet (registered trademark), USB (Universal Serial Bus), Bluetooth (registered trademark), and Wi-Fi (Wireless Fidelity) ( Interfaces such as (registered trademark), FeliCa (registered trademark), PCIe (Peripheral Component Interconnect Express), and IEEE (The Institute of Electrical and Electronics Engineers) standards are used.

  In such a hardware configuration, a program stored in a storage medium such as the ROM 30 or the HDD 40 is read into the RAM 20, and the CPU 10 performs an operation according to the program loaded in the RAM 20, thereby configuring a software control unit. A functional block that realizes the functions of the image forming apparatus 1 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

  Next, the functional configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a block diagram schematically illustrating a functional configuration of the image forming apparatus 1 according to the present embodiment. As shown in FIG. 4, the image forming apparatus 1 according to the present embodiment includes a controller 150, a display panel 157, operation buttons 158, a network I / F 159, and a fixing heater 160.

  The display panel 157 is an output interface that visually displays the state of the image forming apparatus 1 and is an input when the user directly operates the image forming apparatus 1 or inputs information to the image forming apparatus 1 as a touch panel. It is also an interface. That is, the display panel 157 includes a function of displaying an image for receiving an operation by the user. The display panel 157 is realized by the operation device 60 and the display device 70 shown in FIG.

  The operation button 158 is an input interface when the user directly operates the image forming apparatus 1 or inputs information to the image forming apparatus 1. The operation button 158 is realized by the operation device 60 shown in FIG.

  The network I / F 159 is an interface for communicating with an information processing apparatus such as a PC (Personal Computer) operated by the user. The network I / F 159 is realized by the communication I / F 80 shown in FIG.

  The fixing heater 160 is a heater for heating the fixing roller 140 a and the fixing roller 140 b in the fixing unit 140.

  The controller 150 is configured by a combination of software and hardware. That is, the controller 150 includes a software control unit configured by the CPU 10 loading a program stored in a storage medium such as the ROM 30 or the HDD 40 into the RAM 20 and performing operations according to the program, and hardware such as an integrated circuit. Is done.

  The main control unit 151 plays a role of controlling each unit included in the controller 150 and gives a command to each unit of the controller 150.

  The operation display control unit 152 displays information on the display panel 157 or notifies the main control unit 151 of information input via the display panel 157. The main control unit 151 gives a command to each unit of the controller 150 according to the information notified from the operation display control unit 152.

  The input / output control unit 153 inputs information input via the network I / F 159 to the main control unit 151. The main control unit 151 gives a command to each unit of the controller 150 according to the information input from the input / output control unit 153.

  The voltage measurement unit 154 measures the output voltage value of an AC (Alternating Current) power source 2 that is a commercial power source or a household power source connected to the image forming apparatus 1. The detailed functional configuration of the voltage measuring unit 154 will be described later with reference to FIG.

  The setting information storage unit 155 stores an ON duty ratio determination table. Here, the ON duty ratio determination table will be described.

  As described above, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the ON duty ratio of the fixing heater 160 is lower than the ON duty ratio during normal operation, and the voltage drop amount of the power supply at that time And the ON duty ratio is determined according to the measured voltage drop amount. At this time, a table for determining the ON duty ratio of the fixing heater 160 from the measured voltage drop amount is an ON duty ratio determination table. Details of the ON duty ratio determination table will be described later with reference to FIG.

  The heating control unit 156 controls the heating of the fixing heater 160 by controlling the power supply to the fixing heater 160 in accordance with the control of the main control unit 151.

  Next, the functional configuration of the voltage measurement unit 154 according to the present embodiment will be described with reference to FIG. FIG. 5 is a block diagram schematically illustrating a functional configuration of the voltage measurement unit 154 according to the present embodiment. As shown in FIG. 5, the voltage measurement unit 154 according to this embodiment includes an AC / DC voltage value conversion unit 161, an A / D converter 162, and an AC voltage value calculation unit 163.

  The AC / DC voltage value converter 161 converts the output voltage value of the AC power source 2 into a DC voltage value. As a result, the image forming apparatus 1 according to the present embodiment can measure the AC voltage value of the AC power supply 2 with the DC voltage value.

  The A / D converter 162 converts the DC voltage value converted by the AC / DC voltage value converter 161 from an analog value to a digital value. As a result, the image forming apparatus 1 according to the present embodiment can calculate the voltage value of the AC power supply 2 with the resolution of the A / D converter 162, and thus can accurately calculate the voltage value.

  The AC voltage value calculation unit 163 calculates the voltage value of the AC power source 2 based on the digital value converted by the A / D converter 162 and inputs the calculation result to the main control unit 151.

  The main control unit 151 determines the ON duty ratio of the fixing heater 160 during printing with reference to the ON duty ratio determination table based on the voltage value notified from the AC voltage value calculation unit 163, and the ON duty The heating controller 156 controls the fixing heater 160 based on the ratio.

  The image forming apparatus 1 according to the present embodiment may be configured not to include the AC / DC voltage value conversion unit 161 but to directly calculate the voltage value of the AC power supply 2 by the A / D converter 162. . Thus, the image forming apparatus 1 according to the present embodiment does not need to convert the voltage value of the AC power source 2 into a DC voltage value.

  Next, the ON duty ratio determination table according to the present embodiment will be described with reference to FIG. FIG. 6 is a diagram illustrating an example of an ON duty ratio determination table according to the present embodiment.

  As described above, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the ON duty ratio of the fixing heater 160 is lower than the ON duty ratio during normal operation, and the voltage drop amount of the power supply at that time And the ON duty ratio is determined according to the measured voltage drop amount. At this time, a table for determining the ON duty ratio of the fixing heater 160 from the measured voltage drop amount is the ON duty ratio determination table shown in FIG.

  In the ON duty ratio determination table according to the present embodiment, the ON duty ratio during normal operation is 100%. For this reason, the image forming apparatus 1 according to the present embodiment, for example, has an ON duty ratio of 60 (%) during normal operation and 7.5 (V) when the voltage drop measured during warm-up is 7.5 (V). Is controlled to 42 (%) to control the heating of the fixing heater 160.

  Further, as described above, the image forming apparatus 1 according to the present embodiment sets the ON duty ratio during normal operation according to the magnitude of the voltage drop amount, the predetermined value a (V), and the predetermined value b (V). It is determined whether printing is performed with the duty ratio lower than the ON duty ratio, printing is performed with the ON duty ratio during normal operation, or power supply to the fixing heater 160 is stopped. That is, in the present embodiment, the predetermined value a is referred to as the first predetermined value and the predetermined value b is referred to as the second predetermined value.

  In the present embodiment, these predetermined values a (V) and b (V) are defined as 5 (V) and 10 (V), respectively, as shown in FIG.

  Here, a method for determining the predetermined values a (V) and b (V) will be described. For example, the output voltage value of the AC power supply 2 necessary for the image forming apparatus 1 to operate normally is set to ± 10 of the rated output voltage value of the AC power supply 2 in consideration of the fluctuation of the output voltage value of the AC power supply 2. (%). For example, if the rated output voltage value of the AC power source 2 is 100 (V), the output voltage value of the AC power source 2 is in the range of 90 (V) to 110 (V) in order for the image forming apparatus 1 to operate normally. Must be in place.

  When the power supply situation is bad, the output voltage value of the AC power supply 2 fluctuates, so that the image forming apparatus 1 does not operate normally if it falls by −10 (%) or more. The absolute value of the voltage drop amount corresponding to −10 (%) is defined as b (V). For example, the rated output voltage value of the AC power source 2 is 100 (V), and the output voltage value of the AC power source 2 required for the image forming apparatus 1 to operate normally is ± 10 (the rated output voltage value of the AC power source 2). %), 10 (V) is defined as b (V).

  Even if the voltage drop amount when the ON duty ratio is lowered is within ± 10% of the rated output voltage value of the AC power supply 2, the voltage drop amount at the ON duty ratio during normal operation is If it does not fall within −10 (%), the image forming apparatus 1 will not operate normally. Therefore, a (V) is determined so that the voltage drop amount at the ON duty ratio during normal operation falls within −10 (%).

  For example, the rated output voltage value of the AC power source 2 is 100 (V), and the output voltage value of the AC power source 2 required for the image forming apparatus 1 to operate normally is ± 10 (the rated output voltage value of the AC power source 2). %). And when the voltage drop amount in the state where ON duty is lowered is 5V, if the ON duty during normal operation is assumed to decrease by 10V, this 10V decrease becomes the upper limit value of ± 10 (%). If the voltage drop exceeds this level, the image forming apparatus 1 will not operate normally. Therefore, 5 (V) is defined as a (V).

  The method for determining the predetermined values a (V) and b (V) described here is an example, and may be determined by other methods.

  Next, ON duty ratio determination processing by the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart for explaining ON duty ratio determination processing by the image forming apparatus 1 according to the present embodiment.

  As shown in FIG. 7, when the image forming apparatus 1 according to the present embodiment performs the ON duty ratio determination process, first, when the power is turned on from the power-off state (S701), the voltage of the AC power source 2 is measured. It is determined whether or not the AC power supply voltage measurement function, for example, the voltage measurement unit 154 has failed (S702).

  Here, the failure of the AC power supply voltage measurement function is assumed to be a case where the voltage value measured by the AC power supply voltage measurement function is fixed at the upper limit or lower limit of the measurement value due to an open failure, a short-circuit failure, or the like. .

  If the image forming apparatus 1 determines in the determination process in S702 that the AC power supply voltage measurement function has failed (S702 / YES), the image forming apparatus 1 notifies the user that the AC power supply voltage measurement function has failed without notifying the user. Notify (S703).

  Then, the image forming apparatus 1 warms up with the ON duty ratio during the normal operation without performing the ON duty ratio determination process (S704), and during the subsequent printing, the fixing heater 160 with the ON duty ratio during the normal operation. The heating operation is performed to perform a printing operation (S705).

  Therefore, the image forming apparatus 1 according to the present embodiment performs the printing operation at the ON duty ratio during the normal operation even if the AC power supply voltage measurement function fails and the ON duty ratio determination process cannot be performed. Is possible.

  On the other hand, when the image forming apparatus 1 determines that the AC power supply voltage measurement function has not failed in the determination processing in S702 (S702 / NO), the image forming apparatus 1 measures the output voltage value of the AC power supply 2 (S706) and the fixing heater 160. The warm-up is performed in a state where the ON duty ratio is lower than the ON duty ratio during normal operation. (S707).

  The ON duty ratio at this time is an ON duty ratio that increases the temperature of the fixing heater 160 to a temperature at which fixing can be performed, and is an ON duty ratio that causes the voltage drop amount of the AC power supply 2 to be less than b (V).

  Then, the image forming apparatus 1 continues to monitor the output voltage value of the AC power source 2 during the warm-up (S708), and determines the difference between the voltage value at the time when the voltage value is the lowest and the voltage value measured in S703 as the AC power source. 2 is calculated as a voltage drop amount 2 (S709), and the magnitude relationship between the voltage drop amount and the predetermined value b (V) is determined (S710).

  If the image forming apparatus 1 determines that the voltage drop amount is equal to or greater than the predetermined value b (V) in the determination process in S710 (S710 / YES), the image forming apparatus 1 cannot perform a normal printing operation. The power supply is stopped (S711), and a message to that effect is displayed on the display panel 157 (S712).

  Accordingly, the image forming apparatus 1 according to the present embodiment can avoid performing a printing operation in an abnormal state in which the fixing heater 160 does not reach a temperature at which the fixing heater 160 can be fixed. Thus, it is possible to avoid the problem that the operation stops during the printing operation. Further, the image forming apparatus 1 according to the present embodiment can notify the user that the printing operation cannot be normally performed.

  On the other hand, when the image forming apparatus 1 determines that the voltage drop amount is less than the predetermined value b (V) in the determination process in S710 (S710 / NO), the voltage drop amount and the predetermined values a (V), b (V ) Is determined (S713).

  If the image forming apparatus 1 determines that the voltage drop amount is not less than a (V) and less than b (V) in the determination processing in S713 (S713 / YES), the image forming apparatus 1 may operate normally with the ON duty during normal operation. Therefore, the ON duty ratio of the fixing heater 160 is determined based on the voltage drop amount calculated in S709 with reference to the ON duty ratio determination table (S714).

  Since the image forming apparatus 1 cannot perform a normal printing operation at the ON duty ratio during the normal operation, the ON duty ratio determined in S714, that is, the ON duty ratio is lowered during subsequent printing. In this state, the heating control of the fixing heater 160 is performed to perform a printing operation (S715).

  Therefore, in the image forming apparatus 1 according to the present embodiment, the heating control based on the ON duty ratio during the normal operation does not reach the temperature at which the fixing heater 160 can be fixed, or until the temperature at which the fixing heater 160 can be fixed. Even when the time is long, it is possible to avoid a problem caused by a voltage drop by controlling the heating of the fixing heater 160 by lowering the ON duty ratio during normal operation.

  On the other hand, if the image forming apparatus 1 determines that the voltage drop amount is less than a (V) in the determination process in S713 (S713 / NO), the image forming apparatus 1 can normally perform the printing operation without reducing the ON duty ratio. Therefore, during the subsequent printing, the heating operation of the fixing heater 160 is controlled at the ON duty ratio during the normal operation to perform the printing operation (S705).

  Accordingly, in such a case, the image forming apparatus 1 according to the present embodiment controls the heating of the fixing heater 160 with the ON duty ratio during normal operation, thereby allowing time for the fixing heater 160 to reach a fixing temperature. It can be shortened. Thereby, the image forming apparatus 1 according to the present embodiment can improve productivity.

  As described above, in the image forming apparatus 1 according to the present embodiment, as shown in FIG. 1A, the ON duty ratio of the fixing heater 160 is lowered from the ON duty ratio in the normal operation to generate the inrush current. Warm-up is performed in the lowered state, and the voltage drop of the power supply at that time is measured. Then, the image forming apparatus 1 according to the present embodiment determines the ON duty ratio according to the measured voltage drop amount, and thereafter performs a printing operation by controlling the heating of the fixing heater 160 with the determined ON duty ratio. It is configured.

  That is, as shown in FIG. 1B, the image forming apparatus 1 according to the present embodiment has an ON duty ratio when the measured voltage drop amount is not less than a predetermined value a (V) and less than b (V). In a state where the value is lower than the ON duty ratio during normal operation, the fixing heater 160 is heated and controlled to perform a printing operation. This is because when the voltage drop amount is not less than a predetermined value a (V) and less than b (V), the heating control based on the ON duty ratio during normal operation does not reach the temperature at which the fixing roller can be fixed, or the fixing heater This is because it takes a long time to reach a temperature at which 160 can be fixed.

  Therefore, even in such a case, the image forming apparatus 1 according to the present embodiment controls the heating of the fixing heater 160 by lowering the ON duty ratio during the normal operation, thereby causing the above problem caused by the voltage drop. Can be avoided.

  Further, as shown in FIG. 1C, the image forming apparatus 1 according to the present embodiment has an ON duty ratio during normal operation when the measured voltage drop amount is less than a predetermined value a (V). The fixing heater 160 is heated to perform a printing operation. This is because when the voltage drop amount is less than the predetermined value a (V), the time until the fixing roller reaches a temperature at which the fixing roller can be fixed does not become long even with the heating control by the ON duty ratio in the normal operation.

  Therefore, in this case, the image forming apparatus 1 according to the present embodiment shortens the time until the fixing roller reaches a temperature at which the fixing roller can be fixed by controlling the heating of the fixing heater 160 at the ON duty ratio during the normal operation. It becomes possible to do. Thereby, the image forming apparatus 1 according to the present embodiment can improve productivity.

  In addition, as shown in FIG. 1D, the image forming apparatus 1 according to the present embodiment, when the measured voltage drop amount is greater than or equal to a predetermined value b (V), thereafter, Stop power supply. This is because even if the heating control is performed below the ON duty ratio during normal operation, the fixing roller does not reach the temperature at which fixing can be performed.

  Therefore, the image forming apparatus 1 according to the present embodiment can avoid performing a printing operation in an abnormal state in which the fixing roller cannot reach a temperature at which fixing can be performed, and a fixing failure occurs, It is possible to avoid the problem that the operation stops during the printing operation.

  The image forming apparatus performs the ON duty ratio determination process every time when warming up before entering the printing operation. Therefore, it takes a long time from the start of the warming up to the actual starting of the printing operation. It will be lost and productivity will fall.

  Therefore, the image forming apparatus 1 according to the present embodiment performs the ON duty ratio determination process only at the time of warm-up when the power is turned on, and at subsequent printing, the ON duty ratio determination process performed at the time of warm-up when the power is turned on. The fixing heater 160 is controlled to be heated according to the determined ON duty ratio, and a printing operation is performed.

Embodiment 2. FIG.
In the first embodiment, warm-up is performed in a state where the ON duty ratio of the fixing heater 160 is lower than the ON duty ratio during normal operation to reduce the inrush current, and the voltage drop amount of the power supply at that time is measured. The image forming apparatus that determines the ON duty ratio according to the measured voltage drop amount has been described.

  On the other hand, the image forming apparatus 1 according to the present embodiment includes a plurality of fixing rollers, and when the power is turned on, the number of fixing heaters 160 that supply power is limited to perform warm-up while reducing the inrush current. Measure the voltage drop of the power supply.

  The image forming apparatus 1 according to the present embodiment determines the number of the fixing heaters 160 that supply power according to the measured voltage drop amount, and thereafter, supplies power only to the fixing heaters 160 to perform a printing operation. Is configured to do. As a result, the image forming apparatus 1 according to the present embodiment can obtain the same effects as those of the first embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, about the structure which attaches | subjects the code | symbol similar to Embodiment 1, it shall show the same or an equivalent part, and abbreviate | omits detailed description.

  First, an overview of the image forming apparatus 1 according to the present embodiment will be described with reference to FIGS. 8 and 9 are diagrams for explaining the outline of the image forming apparatus 1 according to the present embodiment. Note that a and b in FIGS. 8 and 9 are the same as those in the first embodiment.

  First, as shown in FIG. 8A, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the number of fixing heaters 160 that supply power is limited, and the voltage drop amount of the power supply at that time is determined. taking measurement. The image forming apparatus 1 according to the present embodiment determines the number of the fixing heaters 160 that supply power according to the measured voltage drop amount, and thereafter, supplies power only to the fixing heaters 160 to perform a printing operation. Is configured to do.

  That is, the image forming apparatus 1 according to the present embodiment supplies power when the measured voltage drop amount is not less than a predetermined value a (V) and less than b (V) as shown in FIG. The printing operation is performed in a state where the number of fixing heaters 160 is limited. This is because when the voltage drop amount is not less than a predetermined value a (V) and less than b (V), even if power is supplied to all the fixing heaters 160, the temperature cannot be increased to a temperature at which the fixing roller can be fixed, or fixing. This is because it takes a long time to reach a temperature at which the heater 160 can be fixed.

  Therefore, even in such a case, the image forming apparatus 1 according to the present embodiment can avoid the above-described problem caused by a voltage drop by limiting the number of fixing heaters 160 that supply power. It becomes.

  In addition, as illustrated in FIG. 9A, the image forming apparatus 1 according to the present embodiment supplies power to all the fixing heaters 160 when the measured voltage drop amount is less than a predetermined value a (V). In other words, the same number of fixing heaters 160 as in the normal operation are heated and controlled to perform the printing operation. This is because when the voltage drop amount is less than the predetermined value a (V), even if power is supplied to all the fixing heaters 160, the time until the fixing roller reaches a temperature at which fixing can be performed does not become long.

  Accordingly, in such a case, the image forming apparatus 1 according to the present embodiment supplies power to all the fixing heaters 160 to shorten the time required for the fixing roller to reach a fixing temperature, and is required for fixing. Time can be shortened. Thereby, the image forming apparatus 1 according to the present embodiment can improve productivity.

  In addition, as shown in FIG. 9B, the image forming apparatus 1 according to the present embodiment proceeds to the all fixing heaters 160 when the measured voltage drop amount is equal to or greater than a predetermined value b (V). Stop power supply. This is because even if the number of fixing heaters 160 that supply electric power is limited, the fixing roller does not reach a temperature at which fixing can be performed.

  Therefore, the image forming apparatus 1 according to the present embodiment can avoid performing a printing operation in an abnormal state in which the fixing roller cannot reach a temperature at which fixing can be performed, and a fixing failure occurs, It is possible to avoid the problem that the operation stops during the printing operation.

  Note that the image forming apparatus measures the amount of voltage drop of the power source and determines the number of fixing heaters 160 that supply power every time warm-up before entering the printing operation (hereinafter referred to as “limit number determining process”). In this case, the time from the start of the warm-up to the actual start of the printing operation becomes longer and the productivity is lowered.

  Therefore, the image forming apparatus 1 according to the present embodiment performs the limit number determination process only during warm-up when the power is turned on, and is determined by the limit number determination process performed during warm-up when the power is turned on thereafter. Only the number of fixing heaters 160 are supplied with power to perform a printing operation.

  Next, the limit number determination table according to the present embodiment will be described with reference to FIG. FIG. 10 is a diagram illustrating an example of the limited number determination table according to the present embodiment.

  As described above, the image forming apparatus 1 according to the present embodiment performs warm-up in a state where the number of the fixing heaters 160 that supply power is limited, and measures and measures the voltage drop amount of the power supply at that time. The number of fixing heaters 160 that supply electric power is determined according to the amount of voltage drop. At this time, a table for determining the number of fixing heaters 160 that supply power from the measured voltage drop amount is the limit number determination table shown in FIG.

  Next, limit number determination processing by the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 11 is a flowchart for explaining the limit number determining process by the image forming apparatus 1 according to the present embodiment.

  As shown in FIG. 11, when the image forming apparatus 1 according to the present embodiment performs the limit number determining process, first, when the power is turned on from the power-off state (S1101), the voltage of the AC power source 2 is measured. It is determined whether or not the AC power supply voltage measurement function has failed (S1102).

  If the image forming apparatus 1 determines in the determination process in S1102 that the AC power supply voltage measurement function has failed (S1102 / YES), the image forming apparatus 1 notifies the user that the AC power supply voltage measurement function has failed without notifying the user. Notify (S1103).

  Then, the image forming apparatus 1 performs warm-up while supplying power to all the fixing heaters 160 without performing the limit number determining process (S1104), and supplies power to all the fixing heaters 160 during subsequent printing. The printing operation is performed in the state (S1105).

  Therefore, the image forming apparatus 1 according to the present embodiment controls the heating of the same number of fixing heaters 160 as in the normal operation even when the AC power supply voltage measurement function fails and the limit number determining process cannot be performed. The printing operation can be performed.

  On the other hand, when the image forming apparatus 1 determines in the determination process in S1102 that the AC power supply voltage measurement function has not failed (S1102 / NO), the image forming apparatus 1 measures the output voltage value of the AC power supply 2 (S1106) and supplies power. Warm-up is performed with the number of fixing heaters 160 to be limited limited. (S1107).

  The number of fixing heaters 160 that supply electric power at this time is such that the temperature of the fixing heater 160 rises to a temperature at which fixing is possible, and the number of voltage drops of the AC power supply 2 is less than b (V). is there.

  Then, the image forming apparatus 1 continues to monitor the output voltage value of the AC power source 2 during the warm-up (S708), and determines the difference between the voltage value at the time when the voltage value is the lowest and the voltage value measured in S1103 as the AC power source. 2 is calculated as a voltage drop amount of 2 (S1109), and the magnitude relationship between the voltage drop amount and the predetermined value b (V) is determined (S1110).

  If the image forming apparatus 1 determines that the voltage drop amount is equal to or greater than the predetermined value b (V) in the determination process in S1110 (S1110 / YES), the image forming apparatus 1 cannot perform a normal printing operation. Is stopped (S1111), and a message to that effect is displayed on the display panel 157 (S1112).

  Accordingly, the image forming apparatus 1 according to the present embodiment can avoid performing a printing operation in an abnormal state in which the fixing heater 160 does not reach a temperature at which the fixing heater 160 can be fixed. Thus, it is possible to avoid the problem that the operation stops during the printing operation. Further, the image forming apparatus 1 according to the present embodiment can notify the user that the printing operation cannot be normally performed.

  On the other hand, when the image forming apparatus 1 determines that the voltage drop amount is less than the predetermined value b (V) in the determination process in S1110 (S1110 / NO), the voltage drop amount and the predetermined values a (V), b (V ) Is determined (S1113).

  If the image forming apparatus 1 determines that the voltage drop amount is not less than a (V) and less than b (V) in the determination process in S1113 (S1113 / YES), it is normal if power is supplied to all the fixing heaters 160. Therefore, based on the voltage drop amount calculated in S1109, the number of fixing heaters 160 that supply power is determined with reference to the limit number determination table (S1114).

  Since the image forming apparatus 1 cannot normally perform the printing operation while supplying power to all the fixing heaters 160, power is supplied only to the number of fixing heaters 160 determined in S1114 during subsequent printing. Then, the printing operation is performed (S1115).

  Therefore, in the image forming apparatus 1 according to the present embodiment, the electric power is not supplied to all the fixing heaters 160 until the temperature at which the fixing heaters 160 can be fixed, or until the temperature at which the fixing heaters 160 can be fixed. Even when the period of time becomes longer, it is possible to avoid a problem caused by a voltage drop by limiting the number of fixing heaters 160 that supply power.

  On the other hand, if the image forming apparatus 1 determines in step S1113 that the voltage drop amount is less than a (V) (S1113 / NO), the fixing roller can be fixed even if power is supplied to all the fixing heaters 160. Since the time required to reach a certain temperature does not become long and the printing operation can be performed normally, the printing operation is performed with power supplied to all the fixing heaters 160 during the subsequent printing (S1105).

  Accordingly, in such a case, the image forming apparatus 1 according to the present embodiment supplies power to all the fixing heaters 160 to shorten the time required for the fixing roller to reach a fixing temperature, and is required for fixing. Time can be shortened. Thereby, the image forming apparatus 1 according to the present embodiment can improve productivity.

  As described above, the image forming apparatus 1 according to the present embodiment first performs warm-up with the number of fixing heaters 160 supplying electric power being limited as shown in FIG. Measure the voltage drop of the power supply. The image forming apparatus 1 according to the present embodiment determines the number of the fixing heaters 160 that supply power according to the measured voltage drop amount, and thereafter, supplies power only to the fixing heaters 160 to perform a printing operation. Is configured to do.

  That is, the image forming apparatus 1 according to the present embodiment supplies power when the measured voltage drop amount is not less than a predetermined value a (V) and less than b (V) as shown in FIG. The printing operation is performed in a state where the number of fixing heaters 160 is limited. This is because when the voltage drop amount is not less than a predetermined value a (V) and less than b (V), even if power is supplied to all the fixing heaters 160, the temperature cannot be increased to a temperature at which the fixing roller can be fixed, or fixing. This is because it takes a long time to reach a temperature at which the heater 160 can be fixed.

  Therefore, even in such a case, the image forming apparatus 1 according to the present embodiment can avoid the above-described problem caused by a voltage drop by limiting the number of fixing heaters 160 that supply power. It becomes.

  In addition, as illustrated in FIG. 9A, the image forming apparatus 1 according to the present embodiment supplies power to all the fixing heaters 160 when the measured voltage drop amount is less than a predetermined value a (V). In other words, the same number of fixing heaters 160 as in the normal operation are heated and controlled to perform the printing operation. This is because when the voltage drop amount is less than the predetermined value a (V), even if power is supplied to all the fixing heaters 160, the time until the fixing roller reaches a temperature at which fixing can be performed does not become long.

  Accordingly, in such a case, the image forming apparatus 1 according to the present embodiment supplies power to all the fixing heaters 160 to shorten the time required for the fixing roller to reach a fixing temperature, and is required for fixing. Time can be shortened. Thereby, the image forming apparatus 1 according to the present embodiment can improve productivity.

  In addition, as shown in FIG. 9B, the image forming apparatus 1 according to the present embodiment proceeds to the all fixing heaters 160 when the measured voltage drop amount is equal to or greater than a predetermined value b (V). Stop power supply. This is because even if the number of fixing heaters 160 that supply electric power is limited, the fixing roller does not reach a temperature at which fixing can be performed.

  Therefore, the image forming apparatus 1 according to the present embodiment can avoid performing a printing operation in an abnormal state in which the fixing roller cannot reach a temperature at which fixing can be performed, and a fixing failure occurs, It is possible to avoid the problem that the operation stops during the printing operation.

  Note that the image forming apparatus measures the amount of voltage drop of the power source and determines the number of fixing heaters 160 that supply power every time warm-up before entering the printing operation (hereinafter referred to as “limit number determining process”). In this case, the time from the start of the warm-up to the actual start of the printing operation becomes longer and the productivity is lowered.

  Therefore, the image forming apparatus 1 according to the present embodiment performs the limit number determination process only during warm-up when the power is turned on, and is determined by the limit number determination process performed during warm-up when the power is turned on thereafter. Only the number of fixing heaters 160 are supplied with power to perform a printing operation.

  In the present embodiment, the image forming apparatus 1 that performs the limit number determining process has been described. However, in addition to the limit number determining process, the image forming apparatus 1 according to the present embodiment is described in the first embodiment. The ON duty ratio determination process may be performed.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 AC power supply 10 CPU
20 RAM
30 ROM
40 HDD
50 Dedicated device 60 Operating device 70 Display device 80 Communication I / F
90 Bus 101 Sheet supply tray 102 Separation roller 103 Sheet supply roller pair 104 Sheet supply roller pair 105 Sheet supply roller pair 106 Relay unit 107 Relay roller pair 116 Registration unit 117 Registration roller pair 129 Image forming unit 130 Photosensitive drum 131 Charger 132 Developer 133 Destaticizer 134 Optical writing device 135 Primary transfer roller 136 Conveying belt 137 Drive roller 138 Driven roller 139 Secondary transfer roller pair 140 Fixing unit 141 Branch roller pair 142 Branch claw 143 Discharge roller pair 144 Reverse path entrance roller pair 145 Positive Reverse rotation roller pair 146 Reverse roller pair 147 Reverse roller pair 148 Reverse roller pair 149 Reverse roller pair 150 Controller 151 Main control unit 152 Operation display control unit 1 3 output control unit 154 voltage measuring unit 155 setting information storage unit 156 the heating control unit 157 display panel 158 operation button 159 network I / F
160 Fixing heater 161 AC / DC voltage value conversion unit 162 A / D converter 163 AC voltage value calculation unit

Japanese Patent Laid-Open No. 09-101718

Claims (10)

A fixing heater control method for controlling power supply to a fixing heater in an electrophotographic image forming apparatus,
The warm-up time of the fixing heater, the normal than said at electrostatic Chikarakyo supply to the fixing heater is controlled so that rush current Naru rather small power supply voltage due to an inrush current at power supply during the operation of the image forming apparatus Measure the voltage drop of
A fixing heater control method, wherein power supply to the fixing heater is controlled according to the voltage drop amount during a printing operation by the image forming apparatus.   When the voltage drop amount is greater than or equal to a first predetermined value and less than a second predetermined value that is greater than the first predetermined value, power is supplied to the fixing heater during a printing operation by the image forming apparatus. 2. The power supply to the fixing heater is controlled so that an inrush current that flows when the power is supplied is smaller than an inrush current that flows when electric power is supplied to the fixing heater during normal operation. Fixing heater control method.   3. The power supply to the fixing heater is controlled in a printing operation by the image forming apparatus when the voltage drop amount is less than the first predetermined value as in a normal operation. The fixing heater control method as described.   4. The fixing heater control method according to claim 2, wherein when the voltage drop amount is equal to or greater than the second predetermined value, the power supply to the fixing heater is stopped. 5.   5. The fixing heater control method according to claim 4, wherein, when the voltage drop amount is equal to or greater than the second predetermined value, notification of stopping power supply to the fixing heater is given. Only during warm-up when the image forming apparatus is powered on, the inrush current that flows when supplying power to the fixing heater is smaller than the inrush current that flows when supplying power to the fixing heater during normal operation. To control the power supply to the fixing heater, and measure the voltage drop at that time,
6. The power supply to the fixing heater is controlled in accordance with the amount of voltage drop measured during warm-up when the image forming apparatus is turned on during a printing operation by the image forming apparatus. The fixing heater control method according to any one of the above.   By reducing the ON duty ratio when supplying power to the fixing heater below the ON duty ratio when supplying power to the fixing heater during normal operation, an inrush current that flows when supplying power to the fixing heater is reduced. 2. The fixing heater control method according to claim 1, wherein power supply to the fixing heater is controlled so as to be smaller than an inrush current that flows when power is supplied to the fixing heater during normal operation.   When the voltage drop amount is greater than or equal to a first predetermined value and less than a second predetermined value that is greater than the first predetermined value, during the printing operation by the image forming apparatus, depending on the voltage drop amount The fixing heater control method according to claim 7, wherein an ON duty ratio for supplying electric power to the fixing heater is determined. By limiting the number of fixing heaters that supply power to the number of fixing heaters that supply power during normal operation, the inrush current that flows when supplying power to the fixing heater causes power to be supplied to the fixing heater during normal operation. fixing heater control method according to any one of claims 2 to 5 and 8 and controls the power supply to the fixing heater to be smaller than the inrush current flowing when supplying.   When the voltage drop amount is greater than or equal to the first predetermined value and less than a second predetermined value that is greater than the first predetermined value, the voltage drop amount depends on the voltage drop amount during a printing operation by the image forming apparatus. The fixing heater control method according to claim 9, wherein the number of fixing heaters for supplying electric power is determined.