JP2009020463A - Image forming apparatus and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of securing fixation quality and also suppressing flickering of a fluorescent lamp while shortening a warm-up time and maintaining the reduced power consumption. <P>SOLUTION: Priority is given to turning on a heating heater when the temperature of the heating heater drops and a value measured by a heating thermistor becomes less than a target temperature in a state where a detection temperature of a pressure thermistor is less than a target temperature and a pressure heater is fully turned on. That is, even when the temperature of the pressure heater becomes less than the target temperature, the pressure heater is immediately turned off without performing a through-down control of the pressure heater. Simultaneously, the through-up control of the heating heater is started. When the through-up control is finished, the heating heater is shifted to be fully turned on. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming apparatus control method, and more particularly to an image forming apparatus having a fixing heating roller and a pressure roller, and an image forming apparatus control method.

  An image forming apparatus (MFP (Multi Function Peripheral), facsimile apparatus, copier, printer, etc.) has a print engine, forms an image based on image data, prints it on paper, and outputs it. In order to fix the toner image on the paper, a process of heating and pressurizing (heat fixing) the paper on which the toner image is formed by a heat roller is performed.

  Patent Document 1 below discloses an image forming apparatus that performs fixing phase control in order to suppress voltage fluctuation flicker. In order to suppress harmonic current, a technique is disclosed in which, when the heater is turned on, fixing phase control is first started (soft start), then phase control is performed for a predetermined time with a predetermined duty ratio, and switching to half-wave control with the same duty ratio is performed. Yes.

  Patent Document 2 discloses an image forming apparatus that turns on both the heater and the pressure heater at the time of warm-up and turns on only one after the warm-up is completed, but synchronizes one heater off and the other heater on to the AC zero cross. Is disclosed. As a control unit, a technique for controlling the number of lighting within a unit time by an integral multiple of a half wave is disclosed.

  Patent Document 3 discloses an image forming apparatus having a heating / pressurizing heater and having a phase control mode. One of the heaters is turned off while the exposure lamp is lit, and for the heater to be turned off, the supply power phase angle is immediately switched from 100% to 0% when the exposure lamp is lit, and immediately from 0% to 100 when the exposure lamp is turned off. A technique for switching to% is disclosed.

  Patent Document 4 discloses a fixing phase control in which an even number of cycles is set as one unit for noise reduction, and the conduction angle is gradually increased for each unit, and the conduction angles are equalized for even cycles within the same unit. It discloses about.

  Patent Document 5 discloses a technique for controlling the phase angle of phase control or the time constant of soft start according to the in-machine temperature, the mounting option, and the operation mode.

Patent Document 6 discloses a technique in which the slew-up time for phase control is made variable according to the temperature of the fixing device, and the energization time is gradually increased for each predetermined number of steps.
JP 2004-191710 A JP 2003-195680 A Japanese Patent Laid-Open No. 10-20705 JP-A-10-133504 JP-A-6-242644 JP 2001-5537 A

  However, when the techniques of the cited documents 1 to 3 are used, there is a problem that the fluorescent lamp flickers.

  In order to solve such a problem, when the heater is turned on, fixing phase control is started (soft start), and then the heater is fully turned on.

  In addition, there is a fixing device having a total of three heater lamps, one heater lamp for the narrow roller and one for the wide roller, and one heater lamp for the pressure roller. If the heater wattage is increased in order to shorten the warm-up time, there is a problem that a plurality of heaters cannot be turned on at the same time in order to reduce power consumption.

  In the fixing device having such a configuration, when fixing phase control is introduced to prevent flickering of a fluorescent lamp, time for through-up and through-down is required. When trying to turn on one heater, if another heater is lit, the through-down time of the lit heater must be waited. The ripple of the may become large. In particular, when the temperature of the heater fluctuates, there is a problem that the image quality deteriorates.

  The present invention has been made to solve such a problem, and it is possible to ensure fixing quality and suppress flickering of a fluorescent lamp while reducing power consumption while shortening warm-up time. An object of the present invention is to provide an image forming apparatus and a control method of the image forming apparatus.

  In order to achieve the above object, according to one aspect of the present invention, an image forming apparatus for thermally fixing a toner image on a sheet with a heat roller includes a heating roller having a heater inside, and a pressure roller having a heater inside. Through-up control by gradually increasing the conduction angle for applying a voltage to the heater by the phase control of the AC power supply at the start of energization. 1 control means and second control means for performing through-down control by gradually decreasing the conduction angle for applying a voltage to the heater by phase control of the AC power supply when energization is stopped. When the temperature drops and the heater inside the roller needs to be turned on, the heater inside the roller starts through control and the other If the La internal heater was turned on, it performs control for turning off without the through-down control for the lighting and have the heater.

  Preferably, in the case where the temperature of the heating roller is lowered and the heating heater inside the image forming apparatus needs to be turned on, when the pressure heater inside the pressure roller is turned on, the pressure heater is allowed to pass through. The light is turned off immediately without performing control, and through-up control of the heater is started.

  Preferably, in the case where the temperature of the pressure roller is lowered and the lighting heater inside the image forming apparatus needs to be turned on, if the heating heater inside the heating roller is turned on, the heater down control is performed. After the end of the process, the through-up control of the pressure heater is started.

  According to another aspect of the present invention, in a control method for an image forming apparatus in which a toner image on a sheet is thermally fixed by a heat roller, the image forming apparatus includes a heating roller having a heater inside and a pressurizing having a heater inside. Through-up control by gradually increasing the conduction angle for applying voltage to the heater by phase control of the AC power supply at the start of energization, a fixing device equipped with a roller, a circuit that controls the phase angle of the AC power supply to the heater And a second control means for performing through-down control by gradually decreasing the conduction angle for applying a voltage to the heater by phase control of the AC power supply when energization is stopped. When the temperature of the roller falls and the heater inside the roller needs to be lit, start the through-up control of the heater inside the roller. If the other roller inside the heater was lit, the through-down control for the heater lit performs control for turning off without.

  According to these inventions, an image forming apparatus capable of ensuring fixing quality and suppressing flickering of a fluorescent lamp while reducing power consumption while shortening the warm-up time, and a method for controlling the image forming apparatus are provided. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The fixing device of the image forming apparatus includes a heating roller and a pressure roller. Each of the heating roller and the pressure roller has a heater lamp inside. The fixing device performs fixing phase control. When multiple heater lamps cannot be turned on simultaneously, priority is given to turning on the heater, but when the heater is turned on, if the pressure heater is on, the pressure heater controls the fixing phase (through-down). Turn off the light immediately without performing control.

  When fixing phase control is performed to prevent flickering of a fluorescent lamp, time for up-through and down-down is required. In the present embodiment, when a heater is lit, when another heater is lit, it is not necessary to wait for the through-down time of the lit heater. As a result, the temperature drop of the fixing roller can be prevented.

  More specifically, a fixing device having a heater lamp in each of a heating roller and a pressure roller includes a circuit for controlling the phase angle of the AC power source with respect to the heater lamp, and the heater lamp is controlled by phase control of the AC power source at the start of energization. Through-up control is performed by gradually increasing the conduction angle at which a voltage is applied.

  When energization is stopped, through-down control is performed by gradually decreasing the conduction angle to which the voltage is applied.

  When the temperature of one roller falls and the heater lamp needs to be turned on, the heater lamp's through-up control is started and the heater lamp is turned on. If the other heater is turned on, The fixing device includes a controller that immediately turns off the heater lamp that has been turned on without performing through-down control.

  FIG. 1 is a central cross-sectional view of an image forming apparatus according to one embodiment of the present invention.

  Referring to the figure, an image forming apparatus includes a scanner 201 that reads an image from a document, a print engine 213 that forms a color toner image on a sheet based on image data, a paper feed unit 215 that stores the sheet, A fixing unit 203 for fixing the toner image formed on the sheet, and a duplex unit 211 for inverting the sheet on which the image is formed on one side and printing on the back side.

  In the print unit 213, consumable color units (Y, M, C, K) each including a photoconductor and a developing unit are in contact with the intermediate transfer belt.

  The image on the intermediate transfer belt is transferred to a sheet by the secondary transfer unit and conveyed to the fixing device 203. The fixing device 203 includes a heating roller R1 and a pressure roller R2. A heating long heater 205 and a heating short heater 207 are disposed inside the heating roller R1, and a pressure heater 209 is disposed inside the pressure roller R2.

  Further, sensors for detecting the temperature of each roller are arranged in the vicinity of the heater and the pressure heater (described with reference to FIG. 2).

  FIG. 2 is a schematic block diagram illustrating a control configuration of the image forming apparatus.

  The image forming apparatus 100 performs operation settings for various functions, and also displays an operation display unit 102 for confirming the set functions and displaying various warnings, an image reading unit 105 for reading an image into electronic data, and a reading An image processing unit 106 that performs various image processing on the electronic data that has been processed, an image forming unit 107 that prints out the electronic data subjected to the image processing by a known electrophotographic process, and data that stores the electronic data The storage device 108 includes a ROM 103 and a RAM 104 that are used as work areas in various processes, and an overall control unit 101 that comprehensively controls each unit.

  Further, the image forming apparatus includes an I / F unit (interface unit) 109 serving as a window for communicating with other MFPs 112 to 114 through the network 111, the machine status, the number of consumables printed, the operation time, and the like. A main body nonvolatile memory 110 for storing a counter value.

  As for the fixing device, the image forming apparatus includes a fixing phase waveform output signal 118 for gradually increasing the ON time to the fixing device in synchronization with the zero cross signal 119, a heating long heater signal 115, a heating short heater signal 116, and a pressure heater signal. 117 is output.

  The image forming apparatus includes a heating roller temperature detection sensor (thermistor) 120 and a pressure roller temperature detection sensor (thermistor) 121.

  FIG. 3 is a diagram illustrating a heater lighting circuit included in the image forming apparatus.

  Referring to the figure, the heater lighting circuit includes three gates. The gate 301 inputs a heating long heater signal and a phase control signal, and outputs a heating long heater application signal.

  The gate 303 inputs a heating short heater signal and a phase control signal, and outputs a heating short heater application signal.

  The gate 305 inputs a pressure heater signal and a phase control signal, and outputs a pressure heater application signal.

  FIG. 4 is a diagram illustrating a signal waveform when the heating long heater signal of the image forming apparatus is turned ON.

  The signal waveform is shown in negative logic.

  After the heating long heater signal is turned ON (L level), the phase control signal is set to L level after a predetermined time T1 after the first zero cross signal falls. When the next zero cross signal falls, the phase control signal is set to H level, and after a predetermined time T2, the phase control signal is set to L level.

  When the next zero cross signal falls, the phase control signal is set to H level, and after a predetermined time T3, the phase control signal is set to L level. This is repeated, and finally the phase control signal is fixed at the L level, and the heating long heater is turned on.

  At this time, T1> T2> T3>.

  Thereby, the time for which the heating long heater application signal is turned ON can be gradually increased.

  FIG. 5 is a diagram illustrating a timing chart of heater control executed by the image forming apparatus.

  First, since the detected temperature of the pressure thermistor is lower than the target temperature, it is assumed that the pressure heater is fully lit. At this time, since the detected temperature of the heating thermistor is higher than the target temperature, the heater signal is turned off and the pressure heater is continuously turned on to turn off the heater.

  When the temperature of the heating heater falls and the measured value of the heating thermistor falls below the target temperature, lighting of the heater is given priority, so even if the pressure heater temperature is below the target temperature, the pressure heater is not slewed down. Turn off all lights immediately. At the same time, the heater starts up. When the through-up is completed, the heater is turned on completely.

  When the temperature of the heater is lower than the target temperature, the heater is continuously turned on (the pressure heater is continuously turned off).

  When the temperature of the heater exceeds the target temperature, the heater is started to slew down, and after the slew-down is completed, the heater is turned off.

  When the heater is completely turned off, if the temperature of the pressure heater is lower than the target temperature, the pressure heater is started to pass through. When the through-up is completed, the pressure heater is shifted to full lighting.

  Thus, in the present embodiment, only one of the heater and the pressure heater can be turned on, and the other can be turned off.

  Further, when both the temperature of the heater and the pressure heater have not reached the target temperature, the heater can be turned on with priority.

  Further, when the pressure heater is turned on when the heater needs to be turned on, the pressure heater is turned off immediately without being through-down. At the same time, the heater is shifted to a fully lit state by through-up.

  When the heater reaches the target temperature, the heater is shifted to a fully extinguished state by through-down.

  When the heating heater has reached the target temperature and is fully turned off, if the pressure heater has not reached the target temperature, the pressure heater is shifted to the fully lit state by through-up.

  FIG. 6 is a flowchart showing heater control of the image forming apparatus.

  The process of the flowchart of FIG. 6 is repeatedly executed.

  First, the image forming apparatus checks whether a heater ON command has been issued (S101). If an ON command has been issued (YES in S101), it is checked whether it is an ON command to the heater (S103).

  If it is an ON command to the heater (YES in S103), it is checked whether the pressure heater is currently ON (S105).

  If the pressurizing heater is ON (YES in S105), in order to prioritize lighting of the heater, first, the pressurizing heater is forcibly turned off without through-down (S107), and the process returns to the main routine to return to the heater. End control once.

  When the pressure heater is OFF (NO in S105), the heater is turned ON (S109), the heater is started up (S111), the process returns to the main routine, and the heater control is temporarily terminated.

  If the heater heater ON command is not issued in step S103 (NO in S103), since it is a pressure heater ON command, it is determined in step S113 whether the heater is currently OFF.

  If “YES” in the step S113, the pressure heater is turned on (S115), and the through-up of the pressure heater is started (S117). Thereafter, the process returns to the main routine, and the heater control is temporarily terminated.

  If it is determined in step S113 that the heater is in an ON state (NO in S113), the lighting heater is prioritized so that the pressure heater is not lit and the process returns to the main routine as it is, and the heater control is temporarily performed. finish.

  In step S101, when the heater ON command is not issued (NO in S101), first, through-down control is started in both the heater and the pressure heater (S119). Thereafter, when the through-down is completed (YES in S121), the heater is turned off (S123), the pressure heater is turned off (S125), the process returns to the main routine, and the heater control is temporarily terminated.

  If the through-down is not completed (NO in S121), the through-down is continued, the process returns to the main routine, and the heater control is temporarily terminated.

  [Effects of the embodiment]

  As described above, the image forming apparatus according to the present exemplary embodiment includes a fixing device having a heater lamp in each of the heating roller and the pressure roller, and includes a circuit that controls the phase angle of the AC power source with respect to the heater lamp. Slew-up control is performed by gradually increasing the conduction angle for applying a voltage to the heater lamp by phase control of the AC power supply at the start of energization, and gradually decreasing the conduction angle for applying the voltage when energization is stopped. Perform through-down control with.

  When the temperature of one roller falls and it is necessary to turn on the heater lamp, through-up control of the heater lamp of that roller is started and the heater lamp is turned on. If other heater lamps are lit, the heater lamps that have been lit are immediately turned off without performing through-down control.

  Also, when the temperature of the heating roller falls and the heater heater lamp needs to be turned on, if the pressure heater lamp is turned on, the heater is immediately turned off without performing the through-down control of the pressure heater lamp. The lamp through-up control is started and the heater lamp is turned on.

  Also, when the temperature of the pressure roller falls and the lighting of the pressure heater lamp is required, if the heater heater lamp is lit, the pressure heater is waited for the through-down of the heater heater lamp to end. The lamp through-up control is started and the pressure heater lamp is turned on.

  According to such a configuration, fixing quality can be reduced while reducing power consumption and suppressing flickering of fluorescent lamps even if multiple fixing lamps with large wattage are used to shorten the warm-up time of the fixing unit when the power is turned on. Can be provided.

  In the prior art, fixing phase control is not performed, but the number of lighting within a unit time is controlled by an integral multiple of a half wave to suppress flicker, and fixing phase control is performed to suppress flicker when the heater is turned on. There was a technology to switch to half-wave control with a predetermined duty ratio. However, the half-wave control cannot suppress the flickering of the fluorescent lamp.

  Also, in an apparatus having an exposure lamp and a plurality of fixing lamps and having a phase control mode, one of the heaters is turned off while the exposure lamp is lit, and the supply power phase when the exposure lamp is lit for the heater to be turned off. A technique has been proposed in which the angle is immediately switched from 100% to 0%, and when the exposure lamp is turned off, the angle is immediately switched from 0% to 100%. However, if the phase control is not performed when the lamp is lit, the flickering of the fluorescent lamp cannot be suppressed.

  On the other hand, in the present embodiment, it is possible to provide an image forming apparatus having a fixing device that secures fixing quality and suppresses flickering of a fluorescent lamp while shortening the warm-up time and reducing the power consumption. Become.

  [Others]

  The present invention can be implemented for an image forming apparatus such as an MFP, a facsimile machine, and a copying machine.

  Further, the processing in the above-described embodiment may be performed by software or by using a hardware circuit.

  In addition, a program for executing the processing in the above-described embodiment can be provided, and the program is recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, and a memory card and provided to the user. You may decide to do it. The program may be downloaded to the apparatus via a communication line such as the Internet.

  In addition, it should be thought that the said embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a central cross-sectional view of an image forming apparatus in one embodiment of the present invention. 3 is a schematic block diagram illustrating a control configuration of the image forming apparatus. FIG. It is a figure which shows the heater lighting circuit which an image forming apparatus has. It is a figure which shows a signal waveform when the heating long heater signal of an image forming apparatus is set to ON. FIG. 4 is a timing chart of heater control executed by the image forming apparatus. 3 is a flowchart showing heater control of the image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Image forming apparatus (MFP), 101 Overall control part, 102 Operation display part, 103 ROM, 104 RAM, 105 Image reading part, 106 Image processing part, 107 Image forming part, 108 Data storage device, 109 I / F part, 110 Main body nonvolatile memory, 111 network, 112-114 MFP, 115 heating long heater, 116 heating short heater, 117 pressure heater, 118 fixing phase waveform output, 119 zero cross signal, 120 heating roller temperature detection sensor, 121 pressure roller temperature Detection sensor.

Claims (4)

An image forming apparatus for thermally fixing a toner image on a sheet with a heat roller,
A fixing device including a heating roller having a heater inside, and a pressure roller having a heater inside;
A circuit for controlling a phase angle of an AC power supply with respect to the heater;
First control means for performing through-up control by gradually increasing a conduction angle for applying a voltage to the heater by phase control of the AC power supply at the start of energization;
A second control means for performing through-down control by gradually decreasing the conduction angle for applying a voltage to the heater by phase control of the AC power supply when energization is stopped;
When the temperature inside one roller falls and the heater inside that roller needs to be turned on, start the through-up control of the heater inside that roller, and if the heater inside the other roller is on An image forming apparatus that controls to turn off a heater that has been turned on without performing through-down control.   When the temperature of the heating roller is lowered and the heater inside the heater needs to be turned on, if the pressure heater inside the pressure roller is turned on, the heater is immediately turned off without performing through-down control of the heater. The image forming apparatus according to claim 1, wherein through-up control of the heater is started.   When the temperature of the pressure roller falls and the inside of the pressure heater needs to be turned on, if the heater inside the heating roller is on, wait until the heater's through-down control is completed. The image forming apparatus according to claim 1, wherein through-up control of the pressure heater is started. A control method of an image forming apparatus for thermally fixing a toner image on a sheet with a heat roller,
The image forming apparatus includes:
A fixing device including a heating roller having a heater inside, and a pressure roller having a heater inside;
A circuit for controlling a phase angle of an AC power supply with respect to the heater;
First control means for performing through-up control by gradually increasing a conduction angle for applying a voltage to the heater by phase control of the AC power supply at the start of energization;
A second control means for performing through-down control by gradually decreasing the conduction angle for applying a voltage to the heater by phase control of the AC power supply when energization is stopped;
When the temperature inside one roller falls and the heater inside that roller needs to be turned on, start the through-up control of the heater inside that roller, and if the heater inside the other roller is on A control method for an image forming apparatus, wherein a heater that has been turned on is controlled to be turned off without performing through-down control.

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