JP4298228B2 - Heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention particularly relates to an image forming apparatus for fixing a toner image formed by an electrophotographic process onto a transfer paper.SuitableHeating equipmentIn placeIt is related.
[0002]
[Prior art]
  An image forming apparatus using a conventional electrophotographic process will be described.
[0003]
  A thermal fixing device in an electrophotographic image forming apparatus fixes an unfixed image (toner image) formed on a transfer paper (recording paper) by an image forming means of an electrophotographic process on the transfer paper. A heat roller type heat fixing device using a halogen heater as a heat source and a film heating type heat fixing device using a ceramic surface (heat) heater as a heat source are used.
[0004]
  Generally, these heaters are connected to an AC power source via a switching element such as a triac, and power is supplied by the AC power source. In addition, a fixing device using a heater as a heat source is provided with a temperature detection element, for example, a thermistor temperature sensing element. The temperature detection element detects the temperature of the fixing device, and the sequence controller switches based on the detected temperature information. The power supply to the heater, which is a heat source of the fixing device, is turned on / off by controlling the elements on / off, and thereby the temperature of the fixing device is controlled to the target temperature. . This on / off control for the ceramic surface heater is usually performed by phase control or wave number control of the input commercial power supply.
[0005]
  The phase control or wave number control described above includes a point at which the input commercial power supply is switched from positive to negative or from negative to positive, and is a signal for informing that the power supply voltage has fallen below a certain threshold (hereinafter referred to as “zero cross (ZEROX) signal”). ) To trigger on. In general, this zero-cross signal is a pulse signal obtained by full-wave rectification or half-wave rectification of an input commercial power supply waveform and comparing it with a predetermined threshold voltage. Therefore, the pulse period is the commercial power supply frequency or twice the frequency.
[0006]
  In the case of a zero-cross signal obtained from full-wave rectification, the heater is controlled by triggering at the rising or falling edge that changes from the off state to the on state. In the case of a zero cross signal obtained from half-wave rectification, the heater is controlled by triggering on the edge of a pulse that changes from an off state to an on state and from an on state to an off state.
[0007]
  FIG. 9 is a waveform diagram showing control in the case where phase control is performed by applying a trigger to a zero-cross signal obtained from half-wave rectification, and shows the relationship among a commercial power supply voltage, a jelly-cross signal, an ON signal, and a heater current. As shown in the figure, a trigger is applied to the rising and falling edges of the zero-cross signal, which is a pulse signal, and the phase angles α and β are controlled.
[0008]
[Problems to be solved by the invention]
  By the way, in the above-mentioned zero cross signal, a pulse edge that changes from the off state to the on state or from the on state to the off state is detected, and this is notified to the sequence controller as an interrupt signal. The heater control of the fixing device is performed based on the zero cross signal. In other words, if the pulse period of the zero-cross signal deviates greatly from the commercial power supply frequency or twice the frequency due to the influence of disturbance, power is actually supplied to the heater at a phase angle that is temporarily different from the phase angle calculated by the sequence controller. Will be.
[0009]
  Therefore, for example, when noise is superimposed on the commercial power supply as shown in FIG. 9, the zero cross may be erroneously detected. At this time, if the heater current should be energized with the phase angle β, the zero-cross signal that was detected erroneously is triggered to turn on at the phase angle of β ′, β ″. When the phase angle set when detected is cleared, the heater current is supplied at the phase angle β ″ as shown in the figure.
[0010]
  Conventionally, when such a phenomenon occurs, temperature control is performed by detecting the temperature of the fixing device, so that temperature information is fed back and the fixing device is generally maintained at a predetermined set temperature. However, when the state of the commercial power supply suddenly changes, noise is superimposed on the commercial power supply, the line impedance of the commercial power supply is very large, and the commercial power supply is in a poor environment, or the fixing device When the control gain of the temperature control cannot be increased so as to correct the influence of the disturbance depending on the configuration, if the pulse period of the zero cross signal deviates from the normal period, the temperature control of the fixing device may be affected.
[0011]
  The present invention has been made in view of the above problems, and can control the load to be maintained in a predetermined setting state even in a situation where the state of the input power supply is not good.RukaHeatPlaceIt is intended to provide.
[0012]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention,HeatPlaceNext (1)ofConfigure as follows.
[0013]
  (1)A heater that is supplied with power from an AC power source and generates heat, a temperature detection element that detects the temperature of the heater, a zero-cross detection circuit that detects a zero-cross point of the waveform of the AC power source and outputs a detection signal, and the detection signal Phase control means for outputting an ON signal at a phase angle based on a detection result of the temperature detection element as a trigger, and a TRIAC for bringing the power supply circuit to the heater into a conductive state by the ON signal of the phase control means In the heating device,
When the phase angle based on the detection result of the temperature detection element is less than a predetermined phase angle, the phase control unit is configured to output the detection signal while the zero-cross detection circuit outputs the detection signal. Ignore the detection signal,
When the zero cross detection circuit outputs the detection signal when the phase angle based on the detection result of the temperature detection element is equal to or larger than the predetermined phase angle and the on signal is output, the zero cross detection is performed. When the detection signal from the circuit is inputted, the phase control means turns off the output of the on signal.apparatus.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the drawings.
[0015]
  (First embodiment)
  FIG. 1 is a sectional view showing a configuration of an image forming apparatus according to the present invention, and shows a schematic configuration of a laser printer using an electrophotographic process.
[0016]
  In the figure, reference numeral 101 denotes a printer main body having a cassette 102 for storing the recording paper S, a recording paper presence sensor 103 for detecting the presence of the recording paper S in the cassette 102, and the size of the recording paper S in the cassette 102. There are provided a size sensor 104 composed of a number of micro switches for detecting the recording paper, a paper feed roller 105 for feeding out the recording paper S from the cassette 102, and the like.
[0017]
  A registration roller pair 106 that synchronously conveys the recording paper S is provided downstream of the paper feed roller 105. Further, an image forming unit 108 that forms a toner image on the recording paper S based on the laser beam from the laser scanner unit 107 is provided downstream of the registration roller pair 106.
[0018]
  Further, a fixing device (heating device) 109 for thermally fixing the toner image formed on the recording paper S is provided downstream of the image forming unit 108. A paper discharge sensor 110 that detects the conveyance state, a paper discharge roller 111 that discharges the recording paper S, and a stacking tray 112 on which the recording paper S that has been recorded are stacked are provided. The conveyance reference of the recording paper S is set so as to be centered with respect to the length of the recording paper S in the direction orthogonal to the conveyance direction of the image forming apparatus, that is, the width of the recording paper S.
[0019]
  The laser scanner unit 107 includes a laser unit 113 that emits a laser beam modulated based on an image signal (VDO) transmitted from an external device 131 described later, and a photosensitive drum 117 that outputs a laser beam from the laser unit 113. A polygon motor 114 for scanning upward, an imaging lens 115, a folding mirror 116, and the like are included.
[0020]
  The image forming unit 108 includes the above-described photosensitive drum 117, primary charging roller 119, developing device 120, transfer charging roller 121, cleaner 122, and the like necessary for a known electrophotographic process. The fixing device 109 includes a fixing film 109a, a pressure roller 109b, a ceramic heater 109c provided inside the fixing film 109a, and a thermistor (temperature detecting means) 109d for detecting the surface temperature of the ceramic heater 109c.
[0021]
  Reference numeral 123 denotes a main motor. A driving force is applied to the paper feed roller 105 via a paper feed roller clutch 124, and a resist roller pair 106 via a resist roller 125. Further, image formation including a photosensitive drum 117 is performed. Driving force is also applied to each unit of the unit 108, the fixing device 109, and the paper discharge roller 111.
[0022]
  An engine controller 126 controls the electrophotographic process by the laser scanner unit 107, the image forming unit 108, and the fixing device 109, and controls the conveyance of the recording paper in the printer main body 101.
[0023]
  Reference numeral 127 denotes a video controller, which is connected to an external device 131 such as a personal computer via a general-purpose interface (Centronics, RS232C, etc.) 130. Image information sent through the general-purpose interface 130 is expanded into bit data, and the bit Data is sent to the engine controller 126 via the signal line 128 as a VDO signal. The interface 130 functions as an external output unit for notifying the external device 131 of information.
[0024]
  FIG. 2 is a diagram showing a circuit configuration of the heating device (fixing device 109) of this embodiment, and shows a drive circuit and a control circuit of the ceramic heater 24 (ceramic heater 109c).
[0025]
  In the figure, reference numeral 1 denotes a commercial AC power supply connected to the image forming apparatus. The image forming apparatus applies an input voltage from the AC power supply 1 through an AC filter 2 to the heating element 3 and heating element 20 of the ceramic heater 24. Alternatively, the heating element 3, the heating element 20, or the heating element 40 constituting the ceramic heater 24 is heated by supplying the heating element 40. The AC power supply 1 includes a line impedance, and this line impedance can be equivalently expressed by a resistance component and an inductance component.
[0026]
  The supply of electric power to the heating element 3 is controlled by energization and interruption of the triac 4. The resistors 5 and 6 are bias resistors for the triac 4, and the phototriac coupler 7 is a device for securing a creepage distance between the primary and secondary. Then, the triac 4 is turned on by energizing the light emitting diode of the phototriac coupler 7. The resistor 8 is a resistor for limiting the current of the phototriac coupler 7, and turns on / off the phototriac coupler 7 by the transistor 9. The transistor 9 operates according to the ON1 signal from the engine controller 11 via the resistor 10.
[0027]
  Supply of electric power to the heating element 20 or the heating element 40 is performed by switching to each heating element by the relay 41. Electric power is supplied to the heating element 20 by energizing the coil side of the relay 41, and electric power is supplied to the heating element 40 by interrupting the energization to the coil side of the relay 41. The energization and interruption of the coil side of the relay 41 are on / off controlled by the transistor 43. The transistor 43 operates according to the HSW signal from the engine controller 11 via the resistor 44. The diode 42 protects the transistor 43 by absorbing a back electromotive voltage generated in the coil of the relay 41 when the transistor 43 is turned off.
[0028]
  The power supply to the heating element 20 or 40 selected by the relay 41 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 securing a creepage distance between the primary and secondary. Then, 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 turns on / off the phototriac coupler 16 by the transistor 18. The transistor 18 operates according to the ON2 signal from the engine controller 11 via the resistor 19.
[0029]
  The input power supply voltage from the AC power supply 1 is also input to the zero-cross detection circuit 12 that is a voltage detection means via the AC filter 2, and the zero-cross detection circuit 12 detects it when the input power supply voltage falls below a certain threshold value. The detection signal (pulse signal) is output to the engine controller 11. FIG. 3 shows details of the zero-cross detection circuit 12. Here, the case of a half-wave rectifier circuit is shown.
[0030]
  The AC voltage from the AC power source 1 is input to the zero cross detection circuit of FIG. 3 via the AC filter 2 and is half-wave rectified by the rectifiers 70 and 71. In this drive circuit, the Neutral side is rectified. The half-wave rectified AC voltage is input to the base of the transistor 77 via the resistor 72, the capacitor 75, and the resistors 73 and 76. At this time, if the voltage of the AC power supply 1 is equal to or higher than the slice voltage −V 0 determined by the resistor 72, the capacitor 75, the resistors 73 and 76, and the transistor 77, the transistor 77 is turned off. Thus, the transistor 77 is turned on.
[0031]
  That is, when the neutral side potential is V0 or more higher than the Hot side potential, the transistor 77 is turned on, and the Hot side potential is larger than the Neutral side potential or the potential difference between the Hot side and the Neutral side is V0. The transistor 77 is turned off in the following cases.
[0032]
  The photocoupler 79 is a device for securing a creepage distance between the primary and secondary, and the resistors 78 and 80 are resistors for limiting the current flowing through the photocoupler 79. When the voltage of the AC power supply 1 changes from the positive side to the negative side and the potential difference becomes equal to or lower than the slice voltage −V0, the photocoupler 79 is turned off, and the output voltage of the photocoupler 79 becomes High. At this time, a signal indicating that “the neutral side potential of the AC power supply 1 is greater than the hot side potential” is output (notified) to the engine controller 11 via the resistor 81.
[0033]
  Further, when the voltage of the AC power supply 1 changes from the negative side to the positive side, if the potential difference becomes −V0 or more and the Hot side potential becomes larger than the Neutral side potential, the output voltage of the photocoupler 79 becomes Low (low level). ) At this time, a signal indicating that “the Hot side potential of the AC power supply 1 is equal to or higher than the Neutral potential” is output to the engine controller 11 via the resistor 81. Hereinafter, this signal sent to the engine controller 11 is referred to as a ZEROX signal.
[0034]
  The ZEROX signal is a pulse signal having a signal cycle substantially equal to the frequency of the commercial AC power supply, and the signal level changes according to the potential polarity of the commercial AC power supply. The engine controller 11 detects the rising and falling edges of the ZEROX signal, triggers this edge, and turns on / off the triac 4 or the triac 13 by phase control or wave number control.
[0035]
  In FIG. 2, reference numeral 21 denotes a temperature detecting element for detecting the temperature of the ceramic heater 24 on which the heating element 3, 20 or 40 is formed. For example, a thermistor temperature sensing element is used, and the heating element is provided on the ceramic heater 24. In order to secure an insulation distance with respect to 3, 20, or 40, it is disposed via an insulator having a withstand voltage. The temperature detection element 21 is provided as control amount detection means for detecting the control amount of the ceramic heater 24 that is a load (control target), and a detection signal of the control amount is sent to the engine controller 11.
[0036]
  The temperature detected by the temperature detection element 21 is detected as a voltage divided by the resistor 22 and the temperature detection element 21, and this voltage is sent from the A / D port as a TH signal (detection signal) to the engine controller 11. Entered. That is, the temperature of the ceramic heater 24 is monitored by the engine controller 11 as a TH signal.
[0037]
  And the engine controller 11 calculates the electric power which should be supplied to the heat generating body 3, 20 or 40 which comprises the ceramic heater 24 by comparing the detection temperature of the ceramic heater 24 with the preset temperature set inside. The phase angle (phase control) or wave number (wave number control) corresponding to the supplied power is converted, and an ON1 signal is sent to the transistor 9 or an ON2 signal is sent to the transistor 18 depending on the control conditions.
[0038]
  Furthermore, when the engine controller 11 which is a power supply control means for supplying power to the heating element 3, 20 or 40 fails and the heating element 3, 20 or 40 reaches a thermal runaway, an excessive temperature rise is prevented. As one means for doing so, an excessive temperature rise prevention means 23 is disposed on the ceramic heater 24. For example, a thermal fuse or a thermo switch is used as the excessive temperature rise prevention means 23. When the heating element 3, 20 or 40 reaches 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 excess temperature rise prevention means 23 becomes OPEN, and the heating element 3 , 20 and 40 are de-energized.
[0039]
  Further, when the temperature of the fixing device is controlled by controlling the triac 4 or 13 by the above phase control, when the heater 24 is energized at a predetermined conduction angle by sending an ON signal, the AC power source 1 If the line impedance is very large, the input commercial power supply voltage drops. The magnitude of this voltage drop is determined by the current supplied to the heater 24 and the line impedance.
[0040]
  At that time, as the phase angle at which energization to the heater 24 is turned on is near 90 °, the resistance value of the heater 24 is lower, the line impedance is larger, and particularly the inductance is larger, the phase control is performed. The voltage drop when the heater current conduction is turned on due to increases.
[0041]
  When the voltage drop is increased, the zero-cross detection circuit erroneously detects and notifies the engine controller 11 of an edge of the ZEROX signal that does not occur originally.
[0042]
  Therefore, in this embodiment, as shown in FIG. 4, the ZEROX signal is ignored during the ton, for example, between 50 μsec and 2 msec, while the engine controller 11 is sending an on signal to turn on the triac 4 or 13. I am doing so. By ignoring the ZEROX signal during ton sending this ON signal, false detection of the ZEROX signal that occurs when sending the ON signal can be eliminated, and phase control corresponding to the original commercial frequency is performed. Can do.
[0043]
  FIG. 4 is a waveform diagram showing an outline of the phase control in this embodiment, and shows the relationship among the commercial power supply voltage, the ZEROX signal, the ON signal, and the heater current.
[0044]
  Further, when the phase angle for transmitting the ON signal is deep and it is applied to the edge of the original ZEROX signal, for example, when the signal is turned on at a phase angle of 125 ° or more, as shown in part A in FIG. (ton), the engine controller 11 can detect the original ZEROX signal by monitoring the ZEROX signal. Further, in this case, when the edge of the ZEROX signal is detected when ton 'elapses during the ton period, it is possible to prevent erroneous firing of the next half cycle by setting the transmission time of the on signal to ton'.
[0045]
  As described above, when the switching element that controls the power supply to the heater 24 is turned on at a predetermined phase angle or less, the ZEROX signal is ignored during the period when the on signal is transmitted, and the switching element is turned on at a predetermined phase angle or more. In this case, the ZEROX signal is monitored by the engine controller 11, and when an edge of the ZEROX signal is detected, the on signal is turned off, so that normal heater control can be performed even in a commercial power supply region where the line impedance is large. .
[0046]
  Further, as the phase angle for turning on the energization current to the heater 24 increases and moves away from 90 °, the voltage drop of the input AC power supply generated by the influence of the line impedance when the phase control is turned on becomes smaller. The false detection of is also reduced.
[0047]
  (No.1 referenceExample)
  FIG.Reference example 1It is a figure which shows the structure of the zero cross detection circuit 12 in FIG. Although the case of full wave rectification is shown here, a zero cross detection circuit by half wave rectification may be used as in the first embodiment. In addition, FIG.1 referenceIt is a wave form diagram which shows the phase control of an example.
[0048]
  Although the point which overlaps with a 1st Example is abbreviate | omitted, the alternating voltage from the alternating current power supply 1 of FIG. 2 is input through the AC filter 2, and is full-wave rectified by the rectifier 51. FIG. The full-wave rectified AC voltage is input to the base of the transistor 57 via the resistor 52, the Zener diode 53, the capacitor 55, and the resistor 56. At this time, if the magnitude of the input commercial AC power supply voltage is equal to or lower than the slice voltage Vz determined by the resistor 52, the Zener diode 53, the capacitor 55, the resistor 56, and the transistor 57, the transistor 57 is turned off, and the slice Turns on when the voltage is Vz or higher.
[0049]
  The photocoupler 59 is a device for securing a creepage distance between the primary and secondary, and the resistors 58 and 60 are resistors for limiting the current flowing through the photocoupler 59. When the voltage of the AC power supply 1 is equal to or lower than the slice voltage Vz, the photocoupler 59 is turned off and the voltage of the resistor 60 is Low. At this time, a signal indicating that “the AC power supply 1 is equal to or lower than the slice voltage Vz” is output (notified) to the engine controller 11 via the resistor 61. This signal sent to the engine controller 11 is called a ZEROX signal.
[0050]
  The ZEROX signal is a pulse signal having a pulse period substantially equal to the frequency of the commercial AC power supply. The engine controller 11 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.
[0051]
  Phase control or wave number control is performed using the ZEROX signal monitored by the engine controller 11 as a trigger signal. When the engine controller 11 detects the falling edge of the ZEROX signal as shown in FIG. 6, it detects if the time from the falling edge of the immediately preceding ZEROX signal is within a predetermined time tm. Ignore the ZEROX signal. That is, only when the pulse period of the ZEROX signal is equal to or longer than the predetermined time tm, the ZEROX signal is recognized as a trigger signal, and power supply control to the heater 24 is performed. By ignoring the ZEROX signal whose pulse period is equal to or less than the predetermined time tm, the energization current to the heater 24 is phase-controlled at the phase angle α.
[0052]
  Like thisreferenceIn the example, by detecting the falling edge of the ZEROX signal and ignoring the ZEROX signal within a predetermined time, the zero-cross detection circuit is prevented from being erroneously detected due to noise superimposed on the commercial power supply, and is compatible with the commercial frequency. Power control can be performed.
[0053]
  The predetermined time tm is set to a value larger than twice the maximum value of the assumed commercial power supply frequency.AndIn addition, when used in an image forming apparatus in an assumed commercial power frequency region, it is possible to detect a ZEROX signal that should be detected originally, and to reduce false detection of a ZEROX signal caused by other disturbances and the like. Can do.
[0054]
  For example, when the commercial power supply frequency is assumed to be 40 Hz to 70 Hz, the ZEROX signal is detected every half wave, so that it is detected at a cycle of 12.5 msec to 7.14 msec (80 Hz to 140 Hz). Then, by setting the predetermined time tm set in advance to about 7 msec, it is possible to detect a ZEROX signal that should be detected for a commercial frequency of 40 Hz to 70 Hz. Furthermore, even when the frequency is 40 Hz, noise generated up to a phase angle of 100 ° can be removed, so that it is possible to reduce the influence caused by erroneous detection of the ZEROX signal.
[0055]
  (No.Reference of 2Example)
  FIG.Reference of 2It is a wave form diagram which shows the phase control of an example. In addition, FIG.Reference of 2It is a flowchart which shows the control operation | movement of an example, The control processing shown in this flowchart is performed according to the program previously stored by the engine controller 11 of FIG.
[0056]
  FirstExamples ofAnd the second1 referenceThe point which overlaps with an example is abbreviate | omitted and the case of phase control is demonstrated here.
[0057]
  When the engine controller 11 makes a request to start power supply to the ceramic heater 24 (S201), the falling edge of the ZEROX signal is detected and the pulse interval (cycle) Ts of the ZEROX signal is measured (S202). The pulse interval Ts of this ZEROX signal is measured eight times (S203), an average value is obtained as the pulse interval (pulse period) Ts, and within a predetermined time range set in advance by the engine controller 11, for example, 7.14 mesc-12. Determine if it is 5 msec
(S204).
[0058]
  If it is out of the predetermined time range, the pulse interval of the ZEROX signal is measured again 8 times to determine. If the pulse interval Ts averaged by measurement does not fall within the predetermined time range even after 1 sec has elapsed since the heater drive request has been made (S205), it is considered that the zero-cross detection circuit has failed (S206). End the sequence.
[0059]
  If the pulse interval Ts of the ZEROX signal is within the predetermined time range, power is supplied to the heater 24 and temperature control is started so that the temperature of the fixing device becomes the target temperature (S207). At this time, after detecting the falling edge of the ZEROX signal, an on signal is sent to turn on the triac 4 or 13 at a predetermined phase angle, and phase control is performed. The predetermined phase angle is a phase angle obtained by calculating the power to be input by comparing the target temperature with the detected temperature of the temperature detection element 21 by the engine controller 11 and corresponding to the power.
[0060]
  At this time, the ZEROX signal detected between the detection of the falling edge of the ZEROX signal and the predetermined time (Ts−γ%) is ignored (S208, S209), and the predetermined time (Ts−γ%) has elapsed. If so, the falling edge of the ZEROX signal is detected and phase control is performed (S208, S210).
[0061]
  If there is no heater drive stop request, the phase of the power supplied to the heater 24 is controlled to continue the temperature control of the fixing device (S211). If there is a heater drive stop request, heater drive and temperature control are stopped (S212). As shown in FIG. 7, by ignoring the ZEROX signal whose pulse period is equal to or less than the predetermined time Ts, the current supplied to the heater 24 is phase-controlled at the phase angle α.
[0062]
  Like thisreferenceIn the example, the pulse period Ts of the ZEROX signal that is twice the commercial frequency at the start of heater driving is measured, and a predetermined time (Ts−γ) is detected after detecting the falling edge of the ZEROX signal in the heater supply power. %) Ignores the ZEROX signal, thereby preventing erroneous detection of the zero cross detection circuit due to noise superimposed on the commercial power supply, and performing power control corresponding to the commercial frequency. Here, γ is a correction value when considering the measurement error of the pulse period.
[0063]
  By measuring the pulse period of the ZEROX signal each time the heater is started and ignoring the ZEROX signal detected outside the pulse period, the ZEROX signal that should be detected can be detected. It is possible to reduce false detection of the ZEROX signal caused by the above. In addition, since the power supply state at that time can be reflected by measuring the pulse period of the ZEROX signal every time the heater driving is started, the heater is not affected by this even in a power supply region where the power supply fluctuation or the line impedance is large and the load fluctuation is large. Control can be performed.
[0064]
  (No.3 referencesExample)
  Above1'sExampleAnd first and second reference examples, The edge of the ZEROX signal is detected when the pulse period of the ZEROX signal is detected at a non-predetermined period, or when the heater 24 is turned on at a predetermined phase angle or less during the ON period of the ON signal. In this case, if the detection frequency is equal to or higher than a predetermined frequency set by the engine controller 11, for example, “the power supply situation in which the image forming apparatus is used has a large power supply voltage fluctuation, noise in a sudden change commercial power supply” Is an inferior environment where the line impedance of the commercial power supply is very large, etc. "
Can be recognized.
[0065]
  BookreferenceIn the example, when the engine controller 11 recognizes such a state, the external information output unit provided in the image forming apparatus, for example, a display unit such as a panel is notified that the power supply state is bad and information is given to the user. be able to. Further, by notifying the service center of the image forming apparatus via the Internet that “the power supply state is bad”, it is possible to monitor the state of the commercial power supply for each region. By adopting such a configuration, it is possible to grasp the regionality of the power supply situation, and to help improve the power supply environment by giving information to the user.
[0066]
  As described above, the present inventionThe fruitExamplesAnd reference examplesIn the present invention, the present invention has voltage detection means (zero cross detection means) for notifying the power control means as a pulse signal when it is detected that the input power supply voltage is below a certain threshold value. Based on the signal, an ON signal is transmitted at a predetermined phase angle to control the phase of power supply, and when the ON signal is transmitted during phase control of this power supply, the zero cross detection means notifies the user. When a pulse signal is detected, or when the pulse period of the pulse signal notified from the voltage detection means is other than a predetermined pulse period, the pulse signal is ignored.
[0067]
  As a result, even when the state of the commercial power supply suddenly changes, noise is superimposed on the commercial power supply, or the line impedance of the commercial power supply is very large, the normal state of the commercial power supply is poor. Power control can be performed. And by controlling the heating device that heats the material to be heated by the heating element that is controlled to maintain a predetermined temperature by this power supply device, the original temperature control can be performed without depending on the situation of the commercial power supply. It can be carried out.
[0068]
【The invention's effect】
  As described above, according to the present invention, the state of the input power supply is abruptly changed, noise is superimposed on the input power supply, the line impedance of the input power supply is very large, and the input power supply is in a poor environment. Even in the case of normal, normal power control can be performed.
[0069]
  In addition, by controlling the heating device that heats the material to be heated by the heating element that is controlled so as to maintain a predetermined temperature by the power supply device, the original temperature control is performed without depending on the circumstances of the power supply. be able to.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention.And reference examplesSectional view showing the configuration of the image forming apparatus
FIG. 2 ExampleAnd reference examplesOf the circuit configuration of the heating device
FIG. 3 is a diagram showing a configuration of a zero-cross detection circuit according to the first embodiment.
FIG. 4 is a waveform diagram showing phase control of the first embodiment.
FIG. 51 referenceDiagram showing the configuration of an example zero-cross detection circuit
FIG. 61 referenceWaveform diagram showing example phase control
FIG. 7Reference of 2Waveform diagram showing example phase control
FIG. 8Reference of 2Flow chart showing example control operation
FIG. 9 is a waveform diagram showing phase control of a conventional fixing device.
[Explanation of symbols]
    1 AC power supply
    3 Heating elements
  11 Engine controller
  12 Zero cross detection circuit
  20 Heating element
  21 Temperature sensing element
  23 Over temperature rise prevention means
  24 Ceramic heater
  40 Heating element
101 Printer body
107 Laser scanner
108 Image forming unit
109 Fixing device
109c ceramic heater
109d thermistor
117 Photosensitive drum
120 Developer
126 Engine controller
127 video controller
131 External device

Claims (1)

A heater that is supplied with power from an AC power source and generates heat, a temperature detection element that detects the temperature of the heater, a zero-cross detection circuit that detects a zero-cross point of the waveform of the AC power source and outputs a detection signal, and the detection signal Phase control means for outputting an ON signal at a phase angle based on a detection result of the temperature detection element as a trigger, and a TRIAC for bringing the power supply circuit to the heater into a conductive state by the ON signal of the phase control means In the heating device,
When the phase angle based on the detection result of the temperature detection element is less than a predetermined phase angle, the phase control unit is configured to output the detection signal while the zero-cross detection circuit outputs the detection signal. Ignore the detection signal,
When the zero cross detection circuit outputs the detection signal when the phase angle based on the detection result of the temperature detection element is equal to or larger than the predetermined phase angle and the on signal is output, the zero cross detection is performed. The heating apparatus , wherein the phase control means turns off the output of the ON signal when the detection signal from the circuit is input .

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