JP2011137940A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with a power control method whereby "asymmetrical control inhibition" is satisfied while wasteful consumption of power is reduced, compared with a conventional power control method. <P>SOLUTION: The image forming apparatus is characterized as described below. When a heater-off request arises within one control unit, a fresh power supply pattern 901 of a period shorter than the one control unit is created using a power supply deviation recorded in a recording means, so as to eliminate power supply deviations of a positive half-wave and negative half-wave. Even in course of one control unit, the supply of power to a heating means is controlled following the fresh power supply pattern. The heater is turned off on the finish of the supply of power to the fresh power supply pattern. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus provided with a heating device for heating a toner image on a recording material as a heated material on which a toner image is formed and supported in an image forming apparatus such as a copying machine, a printer, and a fax machine.

  The film heating type heating device or fixing device uses a heater having a low heat capacity. Therefore, when excessive electric power is applied, the temperature rises excessively, resulting in damage to the heater or large overshoot. On the other hand, if the power is too low, the temperature does not rise to the desired heating temperature, the temperature drops quickly, and the temperature ripple increases.

  Therefore, it is necessary to finely control the power to the heater. As a power control method, the heater is energized with one half wave from the zero point (zero cross point) of the AC power source to the next zero point (zero cross point) as a basic unit. Control methods for controlling have been proposed. Use two patterns of 100% energization for one half wave or 100% energization, prepare multiple energization patterns with a predetermined wave number as one control unit, and select one energization pattern from among them depending on the desired power There is a wave number control that performs output. There is also phase control for controlling one half wave with an arbitrary energization amount of 0 to 100%. Furthermore, there is also hybrid control in which the two are combined to control each half-wave of the wave number control energization pattern with an arbitrary energization amount. FIG. 17 shows an example of an energization pattern in each control when energizing at 100%, 50%, and 25%. In addition, the hatching part of a figure represents an electricity supply period.

  In addition, there is a request for “prohibition of asymmetric control” in Section 6.1 of the ITU standard IEC61000-3-2 for harmonic suppression. In order to satisfy this standard, the energization pattern is set so that the energization amount of the positive half wave and the energization amount of the negative half wave within one control unit are the same. Further, for the purpose of this standard, the energization pattern is set so that there is an energization amount of 1 negative half wave which is the same as the energization amount of 1 positive half wave.

  With the recent increase in the speed of image forming apparatuses, the conveyance speed has been increased, and the heating temperature of the fixing device has been increased or the accuracy of the heating temperature has been required to be strict. For this reason, the necessity of performing finer power control is increased, and it is necessary to increase the size of one control unit in order to increase the options of a predetermined wave number of one half wave of the AC waveform of the control unit.

  For example, Patent Document 1 discloses a technique of a power control method in which a plurality of half waves of a commercial power supply are used as one power input pattern, such as wave number control advantageous for harmonic current.

JP 2002-050450 A

  However, when the heating of the fixing device is finished for the end of the conventional printing operation, if the timing is in the middle of one control cycle, the energization pattern of one control cycle is The heating of the fixing device could not be completed until the output was completed, and the energization was continued. As a result, as the energization pattern becomes more complicated and one control cycle becomes longer, there is a problem that this wasteful power consumption increases.

  The invention according to the present application provides an image forming apparatus including a heating device having a power control method that satisfies the above-mentioned “prohibition of asymmetric control” while reducing wasteful power consumption as compared with a conventional power control method. It is in.

  In order to achieve the above object, the invention according to the present application has the following configuration.

  An image forming apparatus that heats and fixes an image on a recording material, wherein a heating body that generates heat when energized from an AC power supply, a zero-cross detection unit that detects a zero-cross of the AC power supply, and a period of the detected zero-cross One half wave of an alternating waveform is used as a unit, and a half wave of a predetermined wave number of 4 or more is used as one control unit, and the same energization amount as one positive half wave within one control unit is energized with one negative half wave. An energization control means for selecting one energization pattern from a plurality of energization patterns satisfying the condition to perform, and controlling energization to the heating body according to the selected energization pattern, and energization deviation between the positive half wave and the negative half wave The energization control unit is configured to record a new energization pattern having a cycle shorter than the one control unit when the heater turn-off request is generated within the one control unit. Energization deviation And generating the current deviation between the positive half wave and the negative half wave, and controlling the current to the heating body according to the new current pattern even in the middle of the one control unit. An image forming apparatus, wherein lighting of a heater is terminated when energization of an energization pattern is terminated.

  According to the present invention, it is possible to provide an image forming apparatus that suppresses wasteful power consumption and satisfies the item 6.1 “prohibition of asymmetric control” of the IEC61000-3-2.

The block diagram explaining the mechanism based on the Example of this invention The block diagram explaining the circuit structure based on the Example of this invention Sectional drawing which shows the structure of the fixing device which concerns on the Example of this invention. The figure which shows the structure of the heater part of the fixing device which concerns on the Example of this invention. 1 is a circuit configuration diagram of a fixing device according to an embodiment of the present invention. Energization pattern diagram according to the first embodiment of the present invention Time chart at the time of energization according to Example 1 of the present invention Time chart when energization termination request according to Embodiment 1 of the present invention The flowchart which concerns on Example 1 of this invention. The flowchart which concerns on Example 1 of this invention. Example of generation of energization small amount processing pattern according to embodiment 1 of the present invention Energization pattern diagram according to the second embodiment of the present invention Data structure diagram for recording energization deviation according to Embodiment 2 of the present invention Time chart at the time of energization according to Embodiment 2 of the present invention FIG. 6 is a data transition diagram for recording an energization deviation during energization according to the second embodiment of the present invention. Time chart when energization termination request according to Embodiment 2 of the present invention The flowchart which concerns on Example 2 of this invention. The flowchart which concerns on Example 2 of this invention. The figure which shows the difference of the conventional fixing control

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to a first exemplary embodiment of the present invention. In FIG. 1, reference numeral 100 denotes a printer main body. Reference numeral 101 denotes a toner cartridge that can be attached to and detached from the printer main body, reference numeral 102 denotes a photosensitive drum as an electrostatic carrier, reference numeral 103 denotes a semiconductor laser as a light source, and reference numeral 105 denotes a rotating polygon mirror that is rotated by a scanner motor 104. Reference numeral 106 denotes a laser beam emitted from the semiconductor laser 103 and scanned on the photosensitive drum 102.

  Reference numeral 107 denotes a charging roller for uniformly charging the surface of the photosensitive drum 102, and reference numeral 108 denotes a developing device for developing the electrostatic latent image formed on the photosensitive drum 102 with toner. Reference numeral 109 denotes a transfer roller for transferring the toner image developed by the developing device 108 to a predetermined recording sheet, 123 denotes a fixing device for heating and fixing the toner image, and 110 denotes a fusion of the transferred toner by heat. A fixing heater (heating member) 111 for the fixing device is a fixing film.

  A paper feed cassette 112 for storing paper is mounted on the printer 100 from the direction of arrow A in FIG. 113 is a paper feed roller, 114 feed roller, and 115 retard roller that feeds paper from the paper feed cassette 112 and feeds it to the transport path when the paper picked up by the paper feed roller is a paper bundle. It is a roller pair for separating into one sheet and sending it out to the conveyance path.

  Reference numeral 116 denotes an intermediate roller for conveying the sheet fed from the cassette to the image forming unit, and 117 is a pre-transfer roller for feeding the conveyed sheet to the photosensitive drum 102. A top sensor 118 synchronizes image writing (recording / printing) on the photosensitive drum 102 and paper conveyance with respect to the fed paper and measures the length of the fed paper in the conveyance direction. It is. Reference numeral 119 denotes a fixing sensor for detecting the presence or absence of a sheet after fixing; 120, a conveyance roller for discharging the fixed sheet to a discharge conveyance path; and 121, a sheet discharged to a discharge tray 122 for stacking the discharged sheets. A discharge roller.

  FIG. 2 shows a block diagram of a circuit configuration of a control system that controls such a mechanism unit. In FIG. 2, reference numeral 201 denotes a printer controller for expanding image code data sent from an external device such as a host computer (not shown) into bit data necessary for printer printing, and reading and displaying printer internal information. .

  Reference numeral 202 denotes an engine controller for controlling each part of the printer engine according to an instruction from the printer controller 201 and notifying the printer controller 201 of internal printer information. Reference numeral 203 denotes a high voltage control unit that performs high voltage output control in each process such as charging, development, and transfer in accordance with an instruction from the engine controller 202. An optical system control unit 204 controls driving / stopping of the scanner motor 104 and lighting of the laser beam in accordance with an instruction from the engine controller 202. Reference numeral 205 denotes a fixing device controller that drives / stops energization of the fixing heater in accordance with an instruction from the engine controller 202. A sensor input unit 206 notifies the controller 202 of the paper presence / absence status of the top sensor 118, the fixing sensor 119, and a paper surface position sensor (not shown). Reference numeral 207 denotes a sheet conveyance control unit that drives / stops a motor / roller or the like for conveying a recording sheet in accordance with an instruction from the printer engine controller 202. This paper conveyance control unit controls driving / stopping of the paper feed roller 113, the feed retard roller pair 116, 117, the pre-transfer roller 117, the photosensitive drum 102, the fixing film 111, the conveyance roller 120, and the paper discharge roller 121 of FIG. It is what controls.

  The fixing device of the image forming apparatus in this embodiment is as shown in FIGS.

  FIG. 3 is a cross-sectional view of the fixing device 123 used in this embodiment. The fixing device 123 is a pressure roller driving type film heating type heating device using an endless film (cylindrical film). Heater 110 as heating means, heater holder 123d having a substantially semi-circular cross-sectional saddle shape in which the heater is fixedly held and having rigidity, and a cylindrical thin heat resistance loosely fitted on heater holder 123d to which heater 110 is attached A film (fixing film) 111 is included. Further, a pressure roller 123b as a rotatable pressure member that forms a fixing nip portion N by mutual pressure contact with the heater 110 with the fixing film 111 interposed therebetween is also provided.

  The pressure roller 123b is driven to rotate at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow by a driving unit. A rotational force acts on the cylindrical fixing film 111 by the pressure friction force at the fixing nip N between the outer surface of the pressure roller and the fixing film 111 due to the rotation of the pressure roller 123b. Then, the fixing film 111 is driven to rotate in the clockwise direction indicated by the arrow around the outer periphery of the heater holder 123d while the inner surface of the fixing film 111 slides in close contact with the downward surface of the heater 110. A sliding grease may be applied to the interface between the fixing film 111 and the heater 110. The heater 110 is a ceramic heater (ceramic surface heater). The heater 110 will be described later.

  The pressure roller 123b is rotationally driven, and the cylindrical fixing film 111 is driven and rotated accordingly. In addition, when the heater 110 is energized, and the heater 110 is heated to a predetermined temperature and the temperature is adjusted, an unfixed toner image is formed between the fixing film 111 and the pressure roller 123b in the fixing nip N. A recording sheet S carrying T is introduced. Then, the toner image carrying surface side of the recording paper S is in close contact with the outer surface of the fixing film 111 at the fixing nip portion N, and the fixing nip portion N is nipped and conveyed together with the fixing film 111. In this nipping and conveying process, the heat of the heater 110 is applied to the recording paper S through the fixing film 111, and the unfixed toner image T on the recording paper S (on the recording material) is heated and pressed on the recording paper S. To melt and fix.

  The recording sheet S that has passed through the fixing nip N is separated from the fixing film 111 by curvature.

  4A is an enlarged cross-sectional view of the heater 110, FIG. 4B is a plan view of the back side of the heater, FIG. 4C is a plan view of the back side of the heater, and FIG. FIG. 4D is a pattern diagram of the extended conductive portion, and FIG. 4D is a plan view of the heater surface side (film sliding surface).

This heater 110 is a back surface heating type ceramic surface heater,
(1) SiC (silicon carbide), AlN (aluminum nitride), Al ₂ O ₃ (alumina), etc. electrical insulating, good thermal conductivity, low thermal capacity ceramic insulating substrate (heater substrate, hereinafter referred to as insulating substrate) 31)
(2) Two energization heating elements (hereinafter referred to as heating elements) 32 and 33 formed on the back surface side of the insulating substrate 31 and power supply electrode portions (hereinafter referred to as electrode portions) for these heating elements. 34, 35, 36 and extended conductive portions (hereinafter referred to as conductive portions) 34a, 35a, 36a
(3) A protective layer 40 made of glass or the like formed by covering the heating elements 32 and 33 and the conductive portions 34a, 35a, and 36a.
Consists of.

  L1 and L2 are the lengths of the heating elements 32 and 33, respectively. a is a central conveyance reference line of the recording paper, A is a paper passing width region of the maximum size paper that can be passed, and B is a paper passing width region of the minimum size paper that can be passed. Reference numerals 51 and 52 denote two power supply connectors. The connector 51 is mounted on the electrode portions 34 and 35 side of the heater 110 to electrically connect the electrode portions 34 and 35 to the heater drive circuit side. The connector 52 is attached to the electrode part 36 side of the heater 110 and electrically connects the electrode part 36 and the heater drive circuit side.

  The heating elements 32 and 33 are formed by baking a paste of a conductive heating resistance material such as Ag / Pd (silver palladium) by patterning by screen printing (thick film printing) or the like.

  The electrode portions 34, 35, 36 and the conductive portions 34 a, 35 a, 36 a are formed by patterning a conductive material paste such as Ag (silver) by screen printing or the like and baking it. The electrode portion 36 is a common electrode for the two heat generating elements 32 and 33, and is electrically connected to one end of each of the heat generating elements 32 and 33 via a branch conductive portion 36a.

  On the protective layer 40, the temperature detection element 21 for detecting the temperature of the heater and the excessive temperature rise prevention means 23 are symmetrical with respect to the central conveyance reference line a of the recording paper, that is, the center in the length direction of the heating elements 32 and 33. And at a position inside the paper passing width region B of the minimum size paper that can be passed.

  In the heater 110, the surface of the insulating substrate 31 opposite to the side on which the heating elements 32, 33, etc. are provided is the surface side (fixing film sliding surface side), and the surface side is directed downward as shown in FIG. It is exposed outside and fixedly supported on the lower surface of the heater holder 123d.

  FIG. 5 shows a drive and control circuit for the heater 110. Reference numeral 1 denotes an AC power supply for connecting the image forming apparatus. The image forming apparatus supplies the AC power to the heating elements 32 and 33 of the heater 110 of the fixing device 123 via the AC filter 2 and the relay 41 to thereby generate the heating elements 32 and 33. 33 is heated.

  The supply of electric power to the heating element 33 is controlled by energization and interruption of the triac 4. Resistors 5 and 6 are bias resistors for the triac 4, and the phototriac coupler 7 is a device for ensuring a creepage distance between the primary and secondary. The triac 4 is turned on by energizing the light emitting diode of the phototriac coupler 7. A resistor 8 is a resistor for limiting the current of the phototriac coupler 7, and the phototriac coupler 7 is turned on / off by the transistor 9. The transistor 9 operates according to the ON1 signal from the engine controller 202 via the resistor 10.

  Supply of electric power to the heating element 32 is controlled by energization and interruption of the triac 13. The resistors 14 and 15 are bias resistors for the triac 13, and the phototriac coupler 16 is a device for ensuring a creepage distance between the primary and secondary. The triac 13 is turned on by energizing the light emitting diode of the phototriac coupler 16. The resistor 17 is a resistor for limiting the current of the phototriac coupler 16, and the phototriac coupler 16 is turned on / off by the transistor 18. The transistor 18 operates according to the ON2 signal from the engine controller 202 via the resistor 19.

  The AC power source 1 is input to the zero cross detection circuit 12 via the AC filter 2. The zero cross detection circuit notifies the engine controller 202 as a pulse signal that the commercial power supply voltage is below a certain threshold value. Hereinafter, this signal sent to the engine controller 202 is referred to as “ZEROX signal”. The engine controller 202 detects the edge of the pulse of the ZEROX signal, and turns on / off the triac 4 or 13 by phase control or wave number control.

  A temperature detection element (for example, a thermistor temperature sensing element) 21 for detecting the temperature of the heater 110 is an insulator having a withstand voltage so that an insulation distance can be secured on the heater 110 with respect to the heating elements 32 and 33. Is arranged through. The temperature detected by the temperature detection element 21 is detected as a partial pressure between the resistor 22 and the temperature detection element 21 and is A / D input to the engine controller 202 as a TH signal. The temperature of the ceramic heater 110 is monitored by the engine controller 202 as a TH signal, and is compared with the set temperature of the heater 110 set in the engine controller 202. Then, the power to be supplied to the heating elements 32 and 33 is calculated, converted into a phase angle (phase control) or wave number (wave number control) corresponding to the supplied power, and the engine controller turns on the transistor 9 according to the control conditions. A signal or ON2 signal is sent to the transistor 18.

  If the temperature detection element 21, the triacs 4, 13 and the like fail and the engine controller 202 determines that the temperature detection or the heater drive circuit has failed, the relay 41 is turned off by turning off the RLD signal, and the heating element 32 and The power supply to 33 is cut off. The relay 41 is turned on / off by the transistor 42. The transistor 42 operates according to the RLD signal from the engine controller 202 via the resistor 43. The resistor 44 is a resistor for protecting the transistor 42. The diode 45 is an element for absorbing a counter electromotive voltage generated when the relay 41 is turned off. Normally, the relay 41 is turned on by the RLD signal before starting the power control to the heating elements 32 and 33 by the ON1 and ON2 signals from the engine controller 202, and controls the power supply to the heating elements 32 and 33. After completion, the signal is turned off by the RLD signal.

  The excessive temperature rise prevention means 23 is, for example, a thermal fuse or a thermo switch, and when the means for supplying and controlling the power to the heating elements 32 and 33 fails and the heating elements 32 and 33 have gone into thermal runaway, the excessive temperature rise prevention means 23 To prevent. When the heating elements 32 and 33 reach a thermal runaway due to a failure of the power supply control means and the excessive temperature rise prevention means 23 exceeds a predetermined temperature, the excessive temperature rise prevention means 23 is opened, and the heating elements 32 and 33 are connected to the heating elements 32 and 33. Power is cut off.

  The common electrode 36 is connected from the HOT side terminal of the AC power supply 1 via the excessive temperature rise prevention means 23. The electrode unit 35 is connected to the TRIAC 4 that controls the heating element 33, and is connected to the Neutral terminal of the AC power supply 1. The electrode unit 34 is electrically connected to the triac 13 that controls the heating element 32, and is connected to the neutral terminal of the AC power supply 1.

  As for the excessive temperature rise prevention means 23, for example, a thermostat is in contact with the insulating substrate 31 surface or the protective layer 40 surface of the heater 110. The position of the thermostat 23 is corrected by the film guide 123 d (FIG. 3), and the thermosensitive surface of the thermostat 23 is in contact with the surface of the heater 110. Although not shown, the temperature detecting element 21 is also in contact with the surface of the heater 110 in the same manner.

  Next, the contents of control for controlling the ON1 and ON2 signals to the heating elements 32 and 33 according to the result of calculating the power to be supplied to the heating elements 32 and 33 in the engine controller 202 will be described. In this embodiment, wave number control for controlling a zero cross signal input from the AC power supply 1 via the zero cross detection circuit 12 as a control base point will be described. In this wave number control, two kinds of combination patterns of 100% energization or 100% non-energization for each half wave, and any one of a plurality of energization patterns provided in advance for a control cycle composed of a predetermined half wave are used. Select and control. In this embodiment, the control cycle is set to 8 half waves, a heater of 1000 W is used with AC 100 V input, and power control is performed at 5 levels from 0 W of the conduction wave number 0 to 1000 W of the conduction wave number 8 in the AC waveform. However, the number of energized waves in one control cycle in the present invention is not limited to eight half waves, and may be four or more half waves.

  FIG. 6 shows an example of an energization pattern at each level as an energization pattern table. In the table of FIG. 6, the vertical column represents the power control level, and the horizontal column represents the wave numbers from 1 to 8 (hereinafter referred to as “wave No”). Also, the numerical values “1” and “0” associated with each wave No of each level in this table represent energization and de-energization, respectively. In this example, control is possible in units of 250 W per half wave. When setting the energization pattern, the accumulated power at the positive half wave and the accumulated power at the negative half wave within one control cycle must be equal to each other in accordance with Section 6.1 “Prohibition of Asymmetric Control” in the IEC 61000-3-2 . Therefore, in FIG. 6, the energization pattern table is created so that the total number of half waves to be energized when the wave No is an odd number and the total number of half waves to be energized when the wave No is an even number at each power control level. Yes.

  The engine controller 202 compares the temperature of the ceramic heater 110 input as a TH signal with the set temperature of the heater 110 set in the engine controller 202, and the power control level to be supplied to the heater in the next control cycle. Is calculated. As a method for calculating the power control level, PID control or the like has been devised, and since it has been introduced in various documents, it is not particularly described here.

  A state in which the engine controller 202 controls the ON1 signal and the ON2 signal will be described with reference to FIG. When the power control level is level 2, the falling edge of the zero cross signal corresponding to the head of the control cycle is detected as input at the timing A in the figure. At this time, the engine controller 202 updates the wave No counter. In the case of timing A, the wave number counter is set to “1” because it is the head of the control cycle. The energization pattern table of FIG. 6 is searched from the power control level “level 2” and the wave No counter “1”, and it is determined that the half-wave is energized. Then, the engine controller 202 outputs a drive pulse to the ON1 signal and the ON2 signal. Thus, the heater 110 is energized and generates heat for one half wave. Next, at the timing B, the engine controller 202 detects the edge of the zero cross signal. Then, the wave number counter is updated to “2”. The energization pattern table of FIG. 6 is searched from the power control level “level 2” and the wave No counter “2”, and it is determined that the half-wave is energized. Next, a drive pulse is output to the ON1 signal and the ON2 signal, whereby the heater 110 is energized and generates heat for one half wave. Then, the engine controller 202 detects the edge of the zero cross signal at timing C. As before, the wave number counter is updated to “3”. The energization pattern table of FIG. 6 is searched from the power control level “level 2” and the wave No counter “3”, and it is determined that the half wave does not energize. The engine controller 202 does not drive the ON1 signal and ON2 signal, and the heater 110 is not energized and does not generate heat during this half-wave. Next, the engine controller 202 detects the edge of the zero cross signal at the timing D. The engine controller 202 updates the wave No counter. Since the wave No counter before the update indicates the end of the control cycle, the wave No counter is set to “1” indicating the beginning of the control cycle. At the same time, since it is the head of the control cycle, the temperature of the ceramic heater 110 to which the power control level is input as a TH signal is compared with the set temperature of the heater 110 set in the engine controller 202 and updated. Here, it is assumed that the new power control level is “level 1”. The energization pattern table of FIG. 6 is searched from the power control level “level 1” and the wave No counter “1”, and it is determined that the half wave does not energize. The engine controller 202 does not drive the ON1 signal and ON2 signal, and the heater 110 is not energized and does not generate heat during this half-wave.

  In the conventional fixing control, symmetry is ensured in one control cycle in order to satisfy the item 6.1 “prohibition of asymmetric control” of the IEC 61000-3-2 of the immunity standard. Therefore, even when there is a request to end the energization of the heater such as at the end of printing, the energization cannot be interrupted in the middle of the control cycle, and the fixing control is continued until one control cycle is completed.

  Therefore, in this embodiment, a means for integrating the energization amount of the positive half wave and the energization amount of the negative half wave is provided for each wave No in one control cycle, and the energization pattern is obtained when there is an energization end request (light-off request). Do not energize according to the table. A new energization pattern is generated by obtaining a difference from the means for integrating the energization amount of the positive half wave and the energization amount of the negative half wave, and a symmetry is ensured. A new fixing control is provided in which the fixing control is completed when the energization is completed. Further, in this embodiment, in order to generate a new energization pattern, means for integrating the energization amount of the positive half wave and the energization amount of the negative half wave for each wave No in one control cycle is used. In addition, it can be realized by means for integrating the difference between the energization amount of the positive half wave and the energization amount of the negative half wave.

  This will be described with reference to the flowcharts of FIGS. FIG. 8 shows a case where an energization end request is received when the control cycle is 8 half-waves, the power control level is level 2 and the control is wave No. The positive half-wave energization counter and the negative half-wave energization counter are counters that are cleared to 0 every control cycle, and are incremented when energized in the positive half-wave or negative half-wave, respectively. When an energization end request is received in the middle of the wave No5, the energization is terminated after waiting for the negative half wave to be energized in the wave No8 as shown in the energization pattern table of FIG. However, the image forming apparatus of the present embodiment compares the positive half-wave energization amount and the negative half-wave energization amount at the time of wave No5, and the total energization amount of the positive half-wave energization amount and the negative half-wave energization amount is A minimum lighting pattern having the same amount is generated as the energization end processing pattern 901.

  The energization end processing pattern includes an energization pattern, a leading wave No, and a wave No in which a value automatically incremented from the leading wave No is set. The maximum value set in the wave No row matches the wave number of the control period. Even if there are too many frames for the energization end processing pattern, a frame in which the wave No exceeds the wave number of the control cycle is not used. Since the original energization pattern is created so that the positive and negative energization amounts coincide within the control cycle, it is sufficient that the maximum size of the energization end processing pattern is the size of the control cycle minus one half wave.

  FIGS. 9A and 9B are flowcharts of energization control in this embodiment. When energization control is started, as a data initialization, the wave No counter is set to the same value as the control cycle (8 in this example), the positive half-wave energization amount and the negative half-wave energization amount are set to 0, and energization end processing is performed. The pattern for use is cleared (S1001). The detection of the Zerox edge is waited (S1002), and when the Zerox edge is detected, the wave No counter is incremented (S1003). The wave No counter is compared with the control cycle “8” (S1004). If the wave No counter exceeds the control cycle, the wave No counter is initialized to 1, and the positive half-wave energization amount and the negative half-wave energization amount. Is cleared to 0 (S1005). The temperature of the ceramic heater 110 input as the TH signal is compared with the set temperature of the heater 110 set in the engine controller 202, and the updated power level is used as the power level to be used within this control cycle. Update (S1006). Using information such as whether the leading wave No of the energization end processing pattern is set, it is checked whether the energization end processing pattern is generated (S1043). If the energization end processing pattern is not generated, the energization is terminated. It is confirmed whether a processing request has occurred (S1007). If an energization end processing request has not occurred, it is confirmed whether energization is performed or not based on the energization level of the energization pattern table and the value of the wave No counter (S1008). If not energized, the process returns to the detection of the Zerox edge in S1002. If energized, the ON1 signal and ON2 signal are turned ON (S1011). It is determined whether or not the wave No is an odd number (S1012). If it is odd, the positive half-wave energization amount is incremented (S1013), and if it is an even number, the negative half-wave energization amount is incremented (S1014). The timer for ON1 signal / ON2 signal control is started (S1015). Wait until the ON time of the ON1 signal / ON2 signal elapses (S1016). Even when the power supply frequency is high, it is necessary to set it shorter than the time of one half wave, and the value is usually 1 msec to 3 msec. After a predetermined time has elapsed, the ON1 signal / ON2 signal is turned OFF (S1017). It waits for edge detection of the Zerox signal again. If there is an energization end request in S1007, the positive half-wave energization amount is compared with the negative half-wave energization amount (S1018). If the positive half-wave energization amount matches the negative half-wave energization amount, the energization amount is compared again in S1009, and the energization control is terminated. If the negative half-wave energization amount is larger in S1018, the difference between the negative half-wave energization amount and the positive half-wave energization amount is stored in the counter in S1019. The wave No updated in S1003 and S1005 is checked to determine whether the wave No is odd or even (S1020). When the wave No is an odd number, the wave No is rewritten to “7”, and the leading wave No of the energization end processing pattern is set to “7” (S1021). An ON → OFF pattern is set as the energization end processing pattern (S1022). The counter stored in S1019 is decremented (S1023). Then, it is determined whether or not the counter is 0 (S1024). If it is not 0, the leading wave No of the energization end processing pattern is decremented by 2 (S1025), and the process proceeds to S1022.

  If the wave No is an even number in S1020, the wave No is rewritten to “6”, and the leading wave No of the energization end processing pattern is set to “6” (S1026). An OFF → ON pattern is set as the energization end processing pattern (S1027).

  Then, the counter stored in S1019 is decremented (S1028). Next, it is determined whether or not the counter is 0 (S1029). If it is not 0, the leading wave No of the energization end processing pattern is decremented by 2 (S1030), and the process proceeds to S1027.

  10A to 10D show examples of energization end processing patterns generated when the counter is 1 or 2 in S1019 and S1020 is odd or even. If the positive half-wave energization amount is larger in S1018, the difference between the positive half-wave energization amount and the negative half-wave energization amount is stored in the counter in S1031. The wave No updated in S1003 and S1005 is checked to determine whether the wave No is odd or even (S1032). When the wave No is an odd number, the wave No is rewritten to “7”, and the leading wave No of the energization end processing pattern is set to “7” (S1033). An OFF → ON pattern is set in the energization end processing pattern (S1034). The counter stored in S1031 is decremented (S1035). It is determined whether or not the counter is 0 (S1036). If it is not 0, the leading wave No of the energization end processing pattern is decremented by 2 (S1037), and the process proceeds to S1034. If the wave No is an even number in S1032, the wave No is rewritten to “8” and the leading wave No of the energization end processing pattern is set to “8” (S1038). An ON → OFF pattern is set as the energization end processing pattern (S1039). The counter stored in S1031 is decremented (S1040). It is determined whether or not the counter is 0 (S1041). If it is not 0, the leading wave No of the energization end processing pattern is decremented by 2 (S1042), and the process proceeds to S1039. Examples of energization end processing patterns generated when the counter is 1 or 2 in S1031 and S1032 is odd or even are shown in FIGS.

  When the energization end processing pattern is generated, the process jumps to the processing of S1009, and the difference between the positive half-wave energization amount and the negative half-wave energization amount is reevaluated. If the energization amounts do not match, it is determined whether the current is energized or not energized from the wave No and the energization end processing pattern (S1010). If not energized, the process returns to the Zerox edge detection in S1002. If energized, the ON1 signal / ON2 signal is turned ON (S1011).

  As described above, when there is an energization end request, the energization pattern for energization termination is generated and energized according to the energization status at that time even within the control cycle, and also depends on the generation timing of the energization end request. However, it is possible to omit the wasteful energization time that is the same as the control cycle.

  In wave number control, in order to perform fine power control, the control cycle must be increased, and the responsiveness decreases. In addition, since the cycle of power on and off at a low lighting ratio becomes long, flicker may be a problem. Further, in the phase control, a sudden rise in current corresponding to the transient characteristic occurs, and noise tends to increase at the power supply terminal. Therefore, taking advantage of both controls, a half wave of a predetermined wave number is set as one control unit as in wave number control, and lighting for each half wave in the one control unit is excluded from 0 to a phase angle at which a sudden current rises. Hybrid control using an arbitrary phase angle of 100% has been proposed. In the present embodiment, application of the present invention in energization control using hybrid control will be described.

  In the wave number control of the first embodiment, when the control cycle is 8 half waves, the power level can be set only in five stages. When the hybrid control of this embodiment is used, even if the energization ratio corresponding to the phase angle that can be adopted in one half wave is limited to only three types of 0%, 20%, and 100%, for example, 1000 W with AC 100 V input When a heater is used, 15 levels of power control are possible as shown in FIG. This also shows that finer power control is possible than in the first embodiment.

  In this embodiment, the control cycle is 8 half waves, the lighting ratio for each half wave is limited to three types of 0%, 20% and 100%, a heater of 1000 W is used with AC 100 V input, and the number of energized waves is 0. Power control is performed in 15 stages from 0 W to 1000 W with a conduction wave number of 8. However, the number of energized waves in one control cycle in the present invention is not limited to eight half waves, and the lighting ratio for each half wave is not limited to three types of 0%, 20%, and 100%.

  When generating the energization end processing pattern, it is necessary to invert the waveform energized with one half wave (one positive half wave) and energize with the other half wave (one negative half wave). In other words, even if the accumulated deviation is 5 times of 20% energization in the positive half wave, even if 100% energization is performed in the negative half wave as the energization end processing pattern, the “asymmetric control prohibition” is satisfied. In other words, it is necessary to carry out 20% energization 5 times in the negative half-wave. In addition, in Section 6.1 “Prohibition of Asymmetric Control” in the immunity standard IEC61000-3-2, the maximum deviation in one control cycle is ± 3 as an allowable range of symmetry in multicycle control such as hybrid control and wave number control. It is determined to be within half a wave. From the above, the data shown in FIG. 12 is sufficient for determining the difference between the positive half-wave energization amount and the negative half-wave energization amount in the hybrid control. FIG. 12 shows the deviation between the energization of the positive half wave and the energization of the negative half wave for three half waves, and an energization ratio (0%, 20%, or 100) according to the energization state is shown in the energization ratio section. %). The data structure of FIG. 12 is called an energization deviation table, and corresponds to means for counting energization amounts in the positive half wave and the negative half wave in the present invention.

  The transition of this data will be described with reference to FIGS. FIG. 13 shows a state of energization in one control cycle when the power control level in FIG. When the wave No is “1” (timing A), the energization amount is 100%. When the wave No is “2” (timing B), the energization amount is 20%. When the wave No is “3” (timing C) and when the wave No is “4” (timing D), the energization amount is 20%. When the wave No is “5” (timing E), the energization amount is 0%. When the wave No is “6” (timing F), the energization amount is 100%. When the wave No is “7” (timing G), the energization amount is 20%. When the wave No is “8” (timing H), the energization amount is 0%.

  FIG. 14 shows the transition of data indicating the deviation of the energization amount at each timing. Since 100% energization is performed at the positive half wave at timing A, 100% is stored in the term of the energization ratio of half wave number 1 of the positive half wave energization deviation. At timing B, 20% is energized in the negative half-wave, so 20% is stored in the half-wave number 1 energization ratio term of the negative half-wave energization deviation. At timing C, 20% energization is performed in the positive half-wave, so a reverse negative half-wave energization record is retrieved, and since there is a record of 20% that is the same energization amount, it is canceled and recorded from the record of the energization deviation in the negative half-wave. Remove%. At timing D, 20% energization is performed in the negative half-wave, so 20% is stored again in the half-wave number 1 energization ratio term of the negative half-wave energization deviation. At timing E, there is no change because the energization amount is 0%. At timing F, 100% energization is performed in the negative half-wave, so the opposite positive half-wave energization record is retrieved and canceled because there is a record of 100% that is the same energization amount. Remove%. At timing G, 20% energization is performed in the positive half-wave, so the opposite negative half-wave energization record is searched and canceled because there is a record of 20% that is the same energization amount. Remove%. At timing H, there is no change because the energization amount is 0%.

  FIG. 15 shows a case where an energization end request is received when the control cycle is 8 half-waves, the power control level is 7 and the wave No is 4. When an energization termination request is received in the middle of wave No4, the energization is terminated after waiting for energization up to wave No8 as shown in the energization pattern table of FIG. However, the image forming apparatus shown in the present embodiment compares the positive half-wave energization amount and the negative half-wave energization amount at the time of wave No4, and the positive half-wave energization amount and the negative half-wave energization amount are the same. Such a minimum lighting pattern is generated as an energization end processing pattern and output instead of the energization pattern table. The energization end processing pattern includes an energization pattern, a leading wave No, and a wave No in which a value automatically incremented from the leading wave No is set. The maximum value set in the wave No row matches the wave number of the control period. Even if there are too many frames for the energization end processing pattern, a frame in which the wave No exceeds the wave number of the control cycle is not used. Since the original energization pattern is created so that the positive and negative energization amounts coincide within the control cycle, it is sufficient that the maximum size of the energization end processing pattern is the size of the control cycle minus one half wave.

  Generation of the energization end processing pattern in this embodiment will be described with reference to the flowcharts of FIGS. 16A and 16B. The same number is attached | subjected about the process same as the flowchart of FIGS. 9-a and 9-b showing energization control of Example 1. FIG.

As initialization processing in energization control, the wave No counter is set to the same value as the control cycle (8 in this example), the energization deviation table is cleared, and the energization end processing pattern is cleared (S1701). The detection of the Zerox edge is waited (S1002), and when the Zerox edge is detected, the wave No counter is incremented (S1003). The wave No counter is compared with the control cycle “8” (S1004). If the wave No counter exceeds the control cycle, the wave No counter is initialized to 1 (S1702). Separately, a power control level is input as a TH signal, and the temperature of the ceramic heater 110 and the set temperature of the heater 110 set in the engine controller 202 are compared to use the updated power level in this control cycle. The level is updated (S1006). Using information such as whether the leading wave No of the energization end processing pattern is set, it is checked whether the energization end processing pattern is generated (S1043). If the energization end processing pattern is not generated, the energization is terminated. It is confirmed whether a processing request has occurred (S1007). If an energization end processing request has not occurred, the energization ratio is determined from the energization pattern table, the energization level, and the value of the wave No counter (S1703). If the energization ratio is 0%, the process returns to the Zerox edge detection in S1002. If the energization ratio is other than 0%, it is determined whether or not the wave No is an odd number (S1012). If it is an odd number, it is confirmed whether or not the same energization ratio as the energization ratio to be energized is recorded on the negative half-wave side of the energization deviation table (S1706). If not recorded, the energization ratio to be energized is recorded on the positive half wave side of the energization deviation table (S1707). If it is recorded, the record of the same power as the energization ratio to be energized is deleted from the record on the negative half wave side of the energization deviation table (S1708). If the wave No is an even number in S1012, it is confirmed whether or not the same energization ratio as the energization ratio to be energized is recorded on the positive half wave side of the energization deviation table (S1709). If not recorded, the energization ratio to be energized is recorded on the negative half wave side of the energization deviation table (S1710). If it is recorded, the record of the same power as the energization ratio to be energized is deleted from the record on the positive half wave side of the energization deviation table (S1711). Whether or not the energization ratio to be energized is 100% is checked (S1712). If it is not 100%, a timer is started to determine the energization start timing (S1713). It waits for the energization start timing (S1714), and when the energization start timing is reached, the ON1 signal / ON2 signal is turned ON (S1011). If the energization ratio is 100% in S1712, the ON1 signal / ON2 signal is immediately turned ON (S1011). The timer for ON1 signal / ON2 signal control is started (S1015). Wait until the ON time of the ON1 signal / ON2 signal elapses (S1016). After a predetermined time elapses, the ON1 signal / ON2 signal is turned OFF (S1017), and the edge detection of the Zerox signal is awaited again.

  When energization termination is requested in S1007, the wave No is copied to the counter, and the counter for searching the positive half wave side and the counter for searching the negative half wave side in the energization deviation table are set to 1, respectively. Set (S1715). The top wave No of the energization end processing pattern is set to the current wave No (S1716). It is determined whether or not the counter is an odd number (S1717). If it is an odd number, it is checked whether the counter for searching the energization deviation table on the negative half wave side does not exceed 3 (S1718). If not, the counter for searching the energization deviation table on the negative half wave side is checked. It is checked whether a value is set in the energization deviation table indicated by (S1719). If the value is set, the energization ratio set in the energization deviation table indicated by the counter for searching the energization deviation table on the negative half-wave side is added to the energization end processing pattern (S1720). The counter for searching the energization deviation table on the negative half-wave side is incremented (S1721), and the counter that copied the wave No is incremented (S1723). It is confirmed whether the counter exceeds 8 (the maximum wave number of the control cycle) (S1730). If not, the process returns to the odd / even judgment of the counter in S1717. If the counter for searching the energization deviation table on the negative half-wave side exceeds 3 in S1718, the process proceeds to incrementing the counter in S1723. If no value is set in the energization deviation table in S1719, the counter for searching the energization deviation table on the negative half-wave side is incremented (S1722), and the energization deviation table on the negative half-wave side in S1718 is retrieved. Return to the check to see if the counter to do so does not exceed 3.

  If the counter is even in S1717, it is checked whether the counter for searching the energization deviation table on the positive half-wave side does not exceed 3 (S1725). If not exceeded, it is checked whether a value is set in the energization deviation table indicated by the counter for searching the energization deviation table on the positive half-wave side (S1726). If the value is set, the energization ratio set in the energization deviation table indicated by the counter for searching the energization deviation table on the positive half-wave side is added to the energization end processing pattern (S1727). The counter for searching the energization deviation table on the positive half-wave side is incremented (S1728), and the counter that copied the wave No is incremented (S1723). It is confirmed whether the counter exceeds 8 (the maximum wave number of the control cycle) (S1730). If not, the process returns to the odd / even judgment of the counter in S1717. If the counter for searching the energization deviation table on the positive half-wave side exceeds 3 in S1725, the process proceeds to incrementing the counter in S1723. If no value is set in the energization deviation table in S1726, the counter for searching the energization deviation table on the positive half wave side is incremented (S1729), and the energization deviation table on the positive half wave side in S1725 is searched. Return to the check to see if the counter to do so does not exceed 3.

  When the energization end processing pattern is generated, the process jumps to the processing of S1704, and it is evaluated whether all the energization deviation tables are cleared or eliminated. If it is not 0, the energization ratio is determined from the wave No and the energization end processing pattern (S1705). If the energization ratio is 0%, the process returns to the detection of Zerox edge in S1002. If the energization ratio is other than 0%, the process proceeds to the odd / even judgment of the wave No in S1012.

  As described above, when there is an energization end request, even if it is within the control cycle, it is generated and energized according to the energization state at that time of the energization pattern for energization end, so that it is the same time as the control cycle at the maximum Only a wasteful energization time can be omitted.

12 Zero cross detection circuit 202 Engine controller 701 Energization pattern (wave number control)
901 Energization end processing pattern

Claims (3)

An image forming apparatus for heating and fixing an image on a recording material,
A heating element that generates heat when energized from an AC power source;
Zero-cross detection means for detecting zero-cross of the AC power supply;
One half wave of an AC waveform corresponding to the detected zero-crossing period is used as a unit, and a half wave having a predetermined wave number of 4 or more is used as one control unit. An energization control means for selecting one energization pattern from a plurality of energization patterns satisfying the condition of energizing the energization amount by one negative half wave, and controlling energization to the heating body according to the selected energization pattern;
Recording means for recording the current deviation between the positive half wave and the negative half wave,
When the heater turn-off request is generated within the one control unit, the energization control means generates a new energization pattern having a shorter cycle than the one control unit by using the energization deviation of the recording means. And the negative half-wave energization deviation is eliminated, and energization of the heating body is controlled according to the new energization pattern even in the middle of the one control unit, and energization of the new energization pattern is completed. The image forming apparatus is characterized in that the lighting of the heater is terminated.   The energization pattern is composed of two combinations of 100% energization for one half wave or 100% energization, and the new energization pattern has a total energization amount for the positive half wave and a total energization amount for the negative half wave. The image forming apparatus according to claim 1, wherein the image forming apparatus generates the same amount.   The energization pattern is configured by combining one half wave with an arbitrary energization amount from 0 to 100%, and the new energization pattern has a total energization amount of the positive half wave and a total energization amount of the negative half wave. 2. The image formation according to claim 1, wherein the pattern is generated so as to have the same amount, and the waveform energized in one half-wave is inverted and the current is energized in the other half-wave. apparatus.

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