JP2005084546A - Fixing control device, fixing control method, fixing control program, recording medium and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing control device which performs the switching control of a fixing heater independent on the frequency when the frequency detection of power source is abnormal and, thereby, is capable of operating equipment without stopping the equipment even when frequency detection is abnormal. <P>SOLUTION: The fixing control device 100 is provided with an AC/DC power source unit 2 which rectifies an alternating current power source 1 used in common to 50 Hz/60 Hz and supplies a direct current power source 8 and a zero-cross signal 7 to a system control board 6 and the system control board 6 which controls the fixing control device 100. The AC/DC power source unit 2 is composed of a switch 4 that switches the alternating current power source 1 and a triac TR5 that provides on-off control of a halogen heater 3 for fixing. The system control board 6 is composed of a CPU 6c that controls the whole, a RAM 6a as a work memory, an I/O interface 6b that controls an external I/O unit, a ROM 6d that stores a control program of the CPU 6c and a phase angle timer 6e that determines the timing of turning the triac TR5 on. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to a method for supplying power to a fixing device used in the image forming apparatus.

In a fixing control device in an image forming apparatus such as a copying machine or a printer, frequency information of a power source is required for the phase control of the heater. When using 50Hz and 60Hz regions like Japan, in order to use the same device regardless of frequency, the power supply frequency is automatically detected correctly, and switching control by the phase angle timer is performed accordingly. Need to change. Therefore, if the frequency detection is not performed normally, the heater lighting control cannot be executed, and the apparatus must be stopped as an abnormal state. In addition, the power supply waveform is not necessarily a clean sine wave, and if a device that consumes large power is operating in the vicinity or if a private power generation facility is used, the waveform will be distorted, the zero-cross signal will be disturbed, and the correct frequency will be Sometimes it could not be detected.
Japanese Patent Application Laid-Open No. 6-202525 discloses an image forming apparatus in which power consumption, temperature rise characteristics, and the like are not changed by fluctuations and differences in input commercial power applied to the apparatus. According to this, in an image forming apparatus such as a copying machine or a printer, power is supplied in response to a print start signal to a heater that generates heat when a commercial power supply is applied, and the temperature of a fixing device including the heater is printed. When the temperature is raised to a sufficient temperature to enter the operation, the energization time is selected based on the detected input commercial power supply voltage value so that the power supplied to the heater per unit time becomes a predetermined value. The power is supplied to the heater.
JP-A-6-202525

As in the past, when the zero-cross signal is disturbed due to external noise or the like and the correct power supply frequency cannot be detected, the fixing heater control is not started, so an error is displayed as an abnormal state, and the device cannot be operated. This has led to an increase in equipment downtime in places where power supply conditions are poor.
In view of such a problem, the present invention enables the operation of the apparatus without stopping even when the frequency detection is abnormal by performing the switching control of the fixing heater independent of the frequency when the frequency detection of the power source is abnormal. An object of the present invention is to provide a fixing control device capable of performing the above.

In order to solve this problem, the present invention provides a heater driven by a 50 Hz / 60 Hz shared AC power supply, a zero cross detection circuit for detecting a zero cross point of the AC power supply, and the zero cross detection circuit Switching means for turning on / off the energization of the heater at a predetermined timing synchronized with the zero cross signal, switching control means for controlling on / off of the switching means at a predetermined timing without depending on a power supply frequency, and A fixing control unit including a zero cross signal as an interrupt signal, wherein the fixing control unit includes a phase angle timer that determines a timing for turning on the switching unit, and a predetermined time for detecting the power supply frequency. A frequency detection timer for monitoring the frequency detection timer when the power is turned on. The number of the interrupt signals within the time set by the controller is counted, the power frequency is determined based on the counted number, and the reference time of the phase angle timer is changed so as to be the determined power frequency It is characterized by doing.
In principle, a fixing control device that controls a heater such as an image forming device detects and switches the vicinity of a zero cross signal of an AC power supply. By connecting this zero-cross signal to the interrupt terminal of the system control board and setting the interrupt operation mode so that an interrupt is generated at the falling edge, an interrupt is generated immediately before the AC signal becomes zero from a positive or negative voltage. Will do. The frequency can be detected by counting the number of zero cross interrupts within a predetermined time. In the present invention, the frequency detection timer counts a predetermined time from the first zero cross interrupt of the frequency detection process, and the count number of zero cross interrupts during this period is counted to determine whether this number is within a predetermined range. The reference time of the phase angle timer is changed based on the determination result.
According to this invention, the number of interrupt signals within the time set by the frequency detection timer is counted, the power supply frequency is determined based on the counted number, and the phase angle timer is set so as to be the determined power supply frequency. Since the reference time is changed, the phase angle is accurately controlled and switched even in the heater used in the 50 Hz / 60 Hz AC power supply.

According to a second aspect of the present invention, the fixing control unit counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and when the counted number of signals is less than a predetermined range, The switching means is turned on / off at a predetermined timing by the switching control means.
In the conventional fixing device, when the frequency of the power source is not detected correctly, the phase angle control is not performed correctly, so the heater control is stopped as a system down. Therefore, in the present invention, in order to prevent the system from going down even in such a case, a switching control means is provided, and the heater is controlled by switching the heater control there.
According to this invention, the number of interrupt signals within the time set by the frequency detection timer is counted, and when the counted number is not within a predetermined range, the switching means is switched at a predetermined timing by the switching control means. Since the system is turned on / off, system downtime can be reduced.
According to a third aspect of the present invention, the fixing control unit counts the number of the interrupt signals within the time set by the frequency detection timer when the power is turned on, and when the counted number of signals is less than a predetermined range, The switching means is turned on / off at a predetermined timing by the switching control means, and the frequency detection timer is operated during the operation to re-determine the power supply frequency.
The heater control by the switching means is an emergency means to the last, and is not necessarily the best control because zero cross control is not performed. Therefore, in the present invention, if the power supply frequency is not correctly controlled, a temporary case due to noise can be considered. Therefore, the retry is performed while the heater is controlled by the switching means for the time being.
According to this invention, when the power supply frequency is not correctly controlled, the retry is performed while the heater is controlled by the switching means, so that a temporary detection error due to noise can be saved.

According to a fourth aspect of the present invention, when the zero cross signal output from the zero cross detection circuit is not generated for a predetermined time, the fixing control unit determines that the fixing control device is abnormal and stops the heater driving. And
It is assumed that the frequency of the power supply is detected in order to correctly perform the heater control. However, if the zero-cross signal from the zero-cross detection circuit is not generated for a predetermined time for some reason, it is determined that the apparatus is abnormal and the heater driving is stopped.
According to this invention, when the zero cross signal from the zero cross detection circuit is not generated for a predetermined time, it is determined that the device is abnormal and the heater driving is stopped. You can prevent things from happening.
According to a fifth aspect of the present invention, the heater is driven by a 50 Hz / 60 Hz common AC power source, a zero cross detection step of detecting a zero cross point of the AC power source, and a predetermined timing synchronized with a zero cross signal detected by the zero cross detection step. A switching step for turning on / off the energization of the heater, a switching control step for controlling on / off of the switching step at a predetermined timing without depending on the power supply frequency, and a fixing control step for using the zero-cross signal as an interrupt signal; The fixing control method includes: a phase angle timer that determines a timing for turning on the switching step; and a frequency detection timer that monitors a predetermined time for detecting the power frequency. The frequency detection timer Counting the number of the interrupt signals within a set time, determining the power supply frequency based on the counted number, and changing the reference time of the phase angle timer so as to become the determined power supply frequency It is characterized by.
According to this invention, there exists an effect similar to Claim 1.

According to a sixth aspect of the present invention, the fixing control step counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and when the counted number of signals is less than a predetermined range, The switching step is turned on / off at a predetermined timing according to the switching control step.
According to this invention, there exists an effect similar to Claim 2.
According to a seventh aspect of the present invention, the fixing control step counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and when the counted number of signals is less than a predetermined range, The switching step is turned on / off at a predetermined timing according to the switching control step, and the frequency detection timer is operated during the operation to re-determine the power supply frequency.
According to this invention, there exists an effect similar to Claim 3.
According to an eighth aspect of the present invention, in the fixing control step, when the zero cross signal output from the zero cross detection circuit is not generated for a predetermined time, the fixing control device is determined to be abnormal and the heater driving is stopped. And
According to this invention, there exists an effect similar to Claim 4.
A ninth aspect is characterized in that the fixing control method according to any one of the fifth to eighth aspects is programmed so as to be controllable by a computer.
According to this invention, the fixing control method of the present invention is programmed according to an OS that can be controlled by the computer, so that any computer equipped with the OS can be controlled by the same processing method.
A tenth aspect of the present invention is a recording medium in which the fixing control program according to the ninth aspect is recorded in a computer-readable format.
According to this invention, by recording the fixing control program on the recording medium in a computer-readable format, the program can be operated anywhere by carrying the recording medium.
According to an eleventh aspect of the present invention, an image forming apparatus includes the fixing control device according to any one of the first to fourth aspects.
According to this invention, since the image forming apparatus includes the fixing control device of the present invention, it is possible to reduce the time during which the system is down due to a heater trouble related to power supply frequency fluctuations.

As described above, according to the first and fifth aspects of the invention, the number of interrupt signals within the time set by the frequency detection timer is counted, and the power supply frequency is determined based on the counted number. Since the reference time of the phase angle timer is changed so as to be the power supply frequency, even the heater used in the AC power supply shared by 50 Hz / 60 Hz is switched with the phase angle accurately controlled.
In the second and sixth aspects, the number of interrupt signals within the time set by the frequency detection timer is counted, and when the counted number is not within a predetermined range, the switching control means performs a predetermined timing. Since the switching means is turned on / off, the system downtime can be reduced.
According to the third and seventh aspects, when the power supply frequency is not correctly controlled, the retry is performed while the heater is controlled by the switching means, so that a temporary detection error due to noise can be saved.
Further, in claims 4 and 8, when the zero cross signal from the zero cross detection circuit is not generated for a predetermined time, it is determined that the apparatus is abnormal and the heater driving is stopped. Unexpected situation can be prevented beforehand.
According to the ninth aspect of the present invention, the fixing control method of the present invention is programmed according to an OS that can be controlled by the computer, so that any computer equipped with the OS can be controlled by the same processing method.
According to another aspect of the present invention, the fixing control program is recorded on a recording medium in a computer-readable format, and the program can be operated anywhere by carrying the recording medium.
According to the eleventh aspect of the present invention, since the image forming apparatus includes the fixing control device of the present invention, it is possible to reduce the time during which the system is down due to a heater trouble related to power supply frequency fluctuations.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
FIG. 1 is a schematic block diagram of a fixing control device of the present invention. This fixing control device 100 is a system for controlling the fixing control device 100, an AC / DC power supply device 2 that rectifies an AC power source 1 shared by 50 Hz / 60 Hz and supplies a DC power source 8 and a zero cross signal 7 to a system control board 6. The AC / DC power supply 2 is configured by a switch 4 that switches the AC power source 1 and a triac TR 5 that controls ON / OFF of the fixing halogen heater 3. The CPU 6c that controls the whole, the RAM 6a as a work memory, the I / O interface 6b that controls the external I / O unit, the ROM 6d that stores the control program for the CPU 6c, and the phase that determines when to turn on the triac TR5 And an angular timer 6e.
The AC / DC power supply device 2 generates DC (24 V, 5 V in this example) necessary for device control from the input AC power supply 1, and has a switching means for the halogen heater 3 that is an AC load, Switching control is performed by a TRIGER signal 9 from the system control board 6. Further, the zero cross point of the AC power supply 1 is detected, and this signal 7 is supplied to the system control board 6. The switching means is composed of a triac TR5, which is turned on by the TRIGER signal 9 and turned off at the zero cross point of the AC power supply during the OFF period of the TRIGER signal 9. Although not shown in this block diagram, the zero cross detection means is also included here.

FIG. 2 is a detection circuit diagram of the zero cross detection means. The zero-cross detection circuit 200 includes a bridge circuit composed of resistors R1 and R2 and a capacitor C1 for the AC power supply 1, a full-wave rectification bridge BR1 that performs full-wave rectification via the bridge circuit, and a photocoupler PC1 that is isolated in an AC manner And a hysteresis inverter IC1 for converting the output signal of the photocoupler PC1 into a digital signal. The input / output of the hysteresis inverter IC1 is pulled up by resistors R3 and R4.
In this circuit, resistors R1 and R2 and a capacitor C1 constitute a low-pass filter and a current limit, and the AC power supply 1 passing therethrough is full-wave rectified by a rectifier bridge BR1. This signal is insulated by the photocoupler PC1 and input to the IC1, which is a hysteresis inverter, to generate the zero cross signal. If the input AC power supply waveform is clean and has no dip, the waveform of each part as shown in FIG. 3 can be obtained. If the signal 13 obtained by inverting the zero cross signal 10 is connected to the IRQ (interrupt) terminal of the CPU of the system control board in FIG. 1, and the interrupt operation mode of the CPU is set so that an interrupt is generated at the falling edge, an AC signal is obtained. An interrupt will occur just before the zero goes from positive or negative voltage to zero. The frequency can be detected by counting the number of zero cross interrupts within a predetermined time. For example, in the present invention, the frequency detection timer is counted for 500 ms from the first zero-crossing interrupt of the frequency detection processing, and if the number of zero-crossing interrupts during this period is 45 to 54, the frequency is determined to be 50 Hz, and 55 to 64 If it is, the frequency is determined to be 60 Hz, and the reference time of the phase angle timer for controlling on / off of the switching means is changed. If the count is out of the above range, it is determined that the frequency detection is abnormal. This frequency detection is very important because phase control is impossible unless the frequency is determined.
FIG. 3 is a diagram showing the waveforms of the respective parts in FIG. The AC input signal 12 is an AC signal, and the voltage changes at a predetermined frequency cycle. The rectified signal 11 is aligned with the voltage in the same direction, and the signal becomes a CPU interrupt signal as a zero cross signal 10. The zero-cross signal 10 becomes the zero-cross signal 10 when the rectified signal 11 is digitized with a predetermined threshold, and is further inverted by the hysteresis inverter IC1 to obtain an interrupt signal as a signal 13.

FIG. 4 is a waveform diagram of the fixing heater rush signal. Since the fixing heater has a low impedance when the temperature is low, a large current flows at the moment when the power is turned on. However, as the temperature rises gradually and the impedance rises, the current decreases as shown in the figure.
FIG. 5 is a flowchart for explaining the start of fixing control and the frequency detection operation. First, when the power is turned on, various settings of the CPU (CPU initialization) are performed (S1), and preparations are made for future control so that all loads are turned off and malfunction of the load does not occur. S2). In the CPU initialization, various timers are set and timer interrupts are permitted. Subsequently, preparation for frequency detection is started. Here, the zero cross interrupt is permitted and the frequency detection start flag is set (S3). Further, the frequency detection timer and the zero cross interrupt counter are cleared to zero (S4). Zero-cross interruption is permitted (S5), and it is monitored whether or not the frequency detection is completed (S6). When the detection is completed, the frequency is determined (S7). It is determined whether or not the result is normal (S8). If the result is normal (YES route in S8), the frequency is set as the detection frequency (S9), the fixing heater phase control operation is performed (S10), and the zero cross abnormality is detected. (S11) Return to step S6 and repeat. If the frequency is abnormal in step S8 (NO route in S8), the frequency detection timer and the zero-cross interrupt counter are cleared, the frequency detection start flag is set (S12), and the fixing heater control is performed when the frequency is abnormal ( S13) Zero cross abnormality detection is performed (S14), and it is monitored whether the frequency detection is completed (S15). If completed, the process returns to step S7 and repeats. If the frequency detection is not completed, the process returns to step S13 and repeats.
In FIG. 5, when the result of frequency detection is not normal detection, the frequency detection timer and the zero-cross interrupt counter are cleared and the frequency detection start flag is set to execute frequency detection again. Thereafter, fixing heater control is executed when frequency detection is abnormal, and the operation of the device is continued. In addition, zero cross abnormality detection is performed to avoid fatal abnormality. Monitors the end of frequency detection while executing fixing heater control and zero-cross error detection when frequency detection is abnormal.When detection is completed, frequency determination is performed again.If normal detection is detected, the process proceeds to fixing heater phase control. Repeat the process so far.

  FIG. 6 is a flowchart of the zero cross interrupt operation. First, it is checked whether or not the frequency detection start flag is set (S21). If it is not set in step S21, the process proceeds to step S23. If it is set, the zero-cross interrupt counter is counted up (S22). Whether or not to perform phase control of the fixing heater is checked (S23). If phase control is performed, the process proceeds to step S24 to check whether or not the fixing heater is turned on (S24). Stop the angle timer (S28) and proceed to step S27. If it is ON timing, set the reference value of the phase angle timer (S25), clear and start the phase angle timer (S26), and zero cross error The counter is cleared (S27). If phase control of the fixing heater is not performed in step S23, the timer is stopped (S29), and it is checked whether or not the fixing heater is on (S30). If it is not on, the timer output is forcibly turned off. (S32) The zero cross abnormality counter is cleared (S27). If the fixing heater is on, the timer output is forcibly turned on (S31), and the zero cross abnormality counter is cleared (S27).

FIG. 7 is a flowchart of the system timer interrupt operation. First, it is checked whether or not the frequency detection flag is set (S31). If it is set, the frequency detection timer is counted up (S32), and step S32 is repeated until a predetermined time elapses (S33). Then, in order to end the frequency detection, the frequency detection start flag is reset (S34), the zero cross abnormality counter is counted up (S35), and the system timer process is performed (S36).
It is detected that the frequency detection start flag is set by the zero cross interrupt by the zero cross signal of FIG. 6, and the zero cross interrupt number counter is counted up. The frequency detection timer is used in the system timer interrupt of FIG. Time 500 ms from the start of frequency detection. When the frequency detection timer counts 500 ms and the frequency detection is completed, the frequency is determined by the value of the zero-cross interrupt counter. The frequency value determined here is used for the subsequent phase control of the fixing heater. When frequency detection is performed normally, phase control is executed. The phase control is based on starting the phase angle timer with reference to the time of occurrence of the zero-cross interrupt, giving a trigger pulse to the triac with a predetermined phase angle timer value, and firing the triac (see FIG. 6).
The phase angle timer for controlling the phase of the fixing heater (halogen heater in FIG. 1) sets a reference value in advance, and when the timer is started, the reference value is automatically compared with the timer value. The thing of the structure which generate | occur | produces is used. When this pulse is used as a trigger for the switching means (triac TR1) in FIG. 1, phase control can be realized. Since the time of the AC half cycle differs between 50 Hz and 60 Hz, the effective voltage applied differs even if the triac is fired after the same time has elapsed from the zero cross point. Here, it is assumed that when the actual power source is 60 Hz, a phase angle timer value that provides a minimum realizable voltage of 50 Hz is given to the timer. In this case, as shown in FIG. 8, a trigger pulse is generated after the zero cross point and a large effective voltage is applied. This prevents normal phase control. Therefore, frequency detection is necessary. The phase control described above cannot be realized when the frequency information is not known as described above. For this reason, the present invention has means for switching the fixing heater that does not use phase control when the frequency is unknown.
When the fixing phase control of FIG. 6 is not used, a trigger pulse for heater control is not output by a timer but is output as a port signal. In the case of the phase control, a trigger pulse is given once in a half cycle of the AC power supply to turn on the heater, whereas in this case, the active level is output during the on time. By controlling in this way, phase control cannot be performed, so soft start cannot be performed, and zero-cross switch may not be performed, but fixing heater control can be performed. This is shown in FIG. That is, when the frequency detection is abnormal, the zero cross signal is mostly erroneously generated rather than the frequency being out of the predetermined range. In such a case, it is conceivable that the phase angle timer restarts each time due to an erroneously generated zero cross signal when phase control is performed, and no voltage is applied to the heater indefinitely. In addition, only a voltage lower than a predetermined voltage may be applied.

In the present invention, in such a case, the trigger always outputs an active level while the heater is on, so that the heater can be fully lit. As a result, the fixing heater control can be continued.
The purpose of phase control when the power is turned on is used for soft start to reduce the inrush current to the fixing heater. Usually, the allowable value of the inrush current is designed so that there is no problem even if the soft start is not performed. For this reason, if there is an abnormality in frequency detection, the fixing heater control is performed regardless of the frequency, and the fixing heater is controlled to reduce the downtime of the device without causing an abnormal stop due to a frequency detection error as in the past. Reduced. In addition, the purpose of performing phase control during normal control is to improve the control accuracy of the fixing temperature, but now it is more meaningful to reduce flicker noise to other devices connected to the same power supply. . Flicker noise means that on / off of energization to a fixing heater, which requires a large amount of power, causes voltage fluctuations in a power supply line, causing light flickering, TV screen fluctuations, and the like. In order to prevent this, it is effective to perform the same soft start as when the power is turned on (see FIG. 9). If the soft start cannot be performed, it may affect other devices, but it is not enough to stop the device.Therefore, the fixing heater is controlled without causing an abnormal stop due to a frequency detection error as in the past. Reduces equipment downtime.
In the fixing heater control, a trigger for turning on / off the heater is output based on the zero cross signal. For this reason, if the zero-cross signal is interrupted, it can be assumed that the trigger cannot be turned on and the fixing heater cannot be turned on, or the fixing heater cannot be turned off and the fixing heater cannot be turned off. . Conventionally, in a situation where the zero cross signal is interrupted, frequency detection is abnormal, and the fixing heater is not turned on. In the present invention, since the fixing heater control is performed even when the frequency detection is abnormal, the heater control is stopped as a zero-cross signal abnormality when the zero-cross signal is interrupted for a predetermined time so as to maintain safety.

FIG. 11 is an operation flowchart of zero cross abnormality detection. The value of the zero-cross abnormality counter is monitored (S41). If the value of this counter exceeds a predetermined value, it is determined that the zero-cross signal has been interrupted, the phase angle timer is stopped (S42), and the phase angle timer output is forcibly turned off. (S43), a safety measure process in the event of an abnormality is executed (S44), and the device is changed to an abnormal state (S45).
That is, the fixing heater is forcibly turned off, and the apparatus is in an abnormal state. The zero cross abnormality counter is counted up by the system timer interrupt of FIG. 7 and cleared by the zero cross interrupt of FIG. For this reason, the value of the zero-cross abnormality counter does not exceed the zero-cross signal interval if a zero-cross signal is generated. Therefore, it is possible to detect that the zero-cross signal has been interrupted by setting a value larger than the zero-cross signal interval assumed as the predetermined value and comparing the counter value with this value.

  FIG. 12 is a schematic diagram showing a schematic structure of an image forming apparatus using the fixing control device of the present invention. The image forming apparatus includes a laser writing unit 121 that writes a latent image on a photoconductor with a laser, a photoconductor 122 that exposes a surface charged by the laser writing unit 121 to form a latent image, and a photoconductor 122 on the photoconductor 122. A cleaner 123 for removing the remaining toner, a charging charger 124 for uniformly charging the photosensitive member 122, a developing device 125 for forming a toner image on the latent image on the photosensitive member, and a transfer for transferring the toner image to a recording sheet. A drum 126, a transfer charger 127 that generates an electric charge for attracting the toner image toward the recording paper, a fixing device 128 that fixes the toner image transferred onto the recording paper, and an information processing unit that controls recording information from the outside 129, a paper feeding device 130 that stores recording paper and feeds the recording paper one by one, a paper discharge tray 131 that discharges the fixed recording paper, and an external interface. And a communication port 132 that is in charge of.

1 is a schematic block diagram of a fixing control device of the present invention. It is a detection circuit diagram of the zero cross detection means of the present invention. It is a figure showing the waveform of each part of FIG. 2 of this invention. It is a waveform diagram of a fixing heater rush signal. 3 is a flowchart for explaining the start of fixing control and the frequency detection operation of the present invention. It is a flowchart of the zero cross interruption operation | movement of this invention. It is a flowchart of the system timer interruption operation | movement of this invention. It is a wave form diagram at the time of controlling the fixing heater of 60 Hz power supply by 50 Hz information of this invention. It is a voltage waveform figure of the soft start of this invention. It is a figure which shows the relationship between the zero cross signal of this invention, and a heater trigger. It is an operation | movement flowchart of the zero cross abnormality detection of this invention. 1 is a schematic diagram illustrating a schematic structure of an image forming apparatus using a fixing control device of the present invention.

Explanation of symbols

  1 AC power supply, 2 AC / DC power supply, 3 Halogen heater, 4 Switch, 5 Triac TR, 6 System control board

Claims (11)

A heater driven by a 50 Hz / 60 Hz common AC power supply, a zero cross detection circuit for detecting a zero cross point of the AC power supply, and energization of the heater at a predetermined timing synchronized with a zero cross signal detected by the zero cross detection circuit A fixing unit comprising: a switching unit that turns off; a switching control unit that controls on / off of the switching unit at a predetermined timing without depending on a power supply frequency; and a fixing control unit that uses the zero-cross signal as an interrupt signal. In the control device,
The fixing control unit includes a phase angle timer that determines a timing to turn on the switching unit, and a frequency detection timer that monitors a predetermined time for the power supply frequency detection,
Counting the number of the interrupt signals within the time set by the frequency detection timer when power is turned on, determining the power frequency based on the counted number, and the phase angle so as to be the determined power frequency A fixing control device that changes a reference time of a timer.   The fixing control unit counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and if the counted signal number is less than a predetermined range, the switching control unit The fixing control apparatus according to claim 1, wherein the switching unit is turned on / off at a predetermined timing.   The fixing control unit counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and if the counted signal number is less than a predetermined range, the switching control unit 3. The fixing control apparatus according to claim 1, wherein the switching unit is turned on / off at a predetermined timing, and the frequency detection timer is operated during the operation to re-determine the power supply frequency.   2. The fixing control unit according to claim 1, wherein if the zero cross signal output from the zero cross detection circuit is not generated for a predetermined time, the fixing control unit determines that the fixing control device is abnormal and stops the heater driving. The fixing control device according to any one of claims 1 to 3. A heater driven by a 50 Hz / 60 Hz AC power source, a zero cross detection step for detecting a zero cross point of the AC power source, and energization of the heater at a predetermined timing synchronized with a zero cross signal detected by the zero cross detection step A fixing step comprising: a switching step for turning off; a switching control step for controlling on / off of the switching step at a predetermined timing without depending on a power supply frequency; and a fixing control step using the zero-cross signal as an interrupt signal. In the control method,
The fixing control method includes a phase angle timer that determines a timing for turning on the switching step, and a frequency detection timer that monitors a predetermined time for the power supply frequency detection,
Counting the number of the interrupt signals within the time set by the frequency detection timer when power is turned on, determining the power frequency based on the counted number, and the phase angle so as to be the determined power frequency A fixing control method characterized by changing a reference time of a timer.   The fixing control step counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and if the counted number of signals is less than a predetermined range, the switching control step The fixing control method according to claim 5, wherein the switching step is turned on / off at a predetermined timing.   The fixing control step counts the number of interrupt signals within a time set by the frequency detection timer when power is turned on, and if the counted number of signals is less than a predetermined range, the switching control step 7. The fixing control method according to claim 5, wherein the switching step is turned on / off at a predetermined timing, and the frequency detection timer is operated during the operation to re-determine the power supply frequency.   6. The fixing control step, when a zero cross signal output from the zero cross detection circuit is not generated for a predetermined time, determines that the fixing control device is abnormal and stops the heater driving. The fixing control method according to claim 1.   9. A fixing control program in which the fixing control method according to claim 5 is programmed so as to be controllable by a computer.   A recording medium in which the fixing control program according to claim 9 is recorded in a computer-readable format.   An image forming apparatus comprising the fixing control device according to claim 1.

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