JP4381948B2 - Power control system, MFP - Google Patents

Description

  The present invention relates to a power supply control system that automatically turns off power when software provided in various electronic devices runs away.

  Various electronic devices such as digital multi-function peripherals and personal computers are provided with a power control system for controlling a power relay with software. In this power supply control system, when the software runs away, the relay may not be controlled. In such a case, there is a problem that the power cannot be normally turned off.

  In relation to such problems, Patent Document 1 discloses that in the data protection device, the processor unit cannot release the energization of the relay after the power switch is turned off due to the software runaway in the system, and the power supply is cut off. A technique for forcibly canceling energization of a relay and canceling the supply of power when it becomes impossible is disclosed.

Patent Document 2 discloses a power supply control circuit capable of shutting off the power supply when a central processing unit (CPU) runs out of control. In this power supply control circuit, a counter provided in the runaway detection circuit is used as means for detecting software runaway. When this counter reaches the full count, it is determined that a runaway has occurred, and the reset circuit is immediately activated to cut off the power. In this power supply control circuit, when the CPU periodically clears the counter, the reset circuit is not activated and it can be confirmed that the software is operating normally.
JP-A-6-282361 (Publication date: October 7, 1994) JP-A 64-82212 (Publication date: March 28, 1988)

  However, in the technique described in Patent Document 1, the energization of the relay is forcibly released only when the power switch is turned off, and is forcibly only within the time of the counter counted from the power switch. The relay cannot be de-energized. In other words, it does not always monitor whether the software is operating normally. Also, in a system that has a FAX transmission reservation mode that operates after the power switch is turned off and requires power control by software independent of the manual power switch, the time for the software to turn off the power is Not determined. For this reason, it is not possible to cope with the method of detecting a software runaway using a limited (constant) counter time.

  In the technique described in Patent Document 2, since the CPU needs to reset the counter periodically, even if it is desired to put the CPU in a standby state for power saving, the counter is periodically reset. It is necessary to return from the standby state. This consumes extra power.

  The present invention has been made in view of the above problems, and its purpose is to constantly monitor software runaway without wastefully operating the CPU, and to turn off the power in the event of software runaway. It is to realize a power supply control system that can do this.

  The inventor of the present application diligently examines the above problems and uses the pulse input of a fixed period as a means for detecting software runaway so that the adverse effects of detection using a counter can be overcome. The headline and the present invention have been completed.

  That is, the power supply control system according to the present invention is a power supply control system provided with a control means for controlling a power supply switch by software, and the control means includes a main control unit as a core of power supply control, software A protection means for outputting a power supply control signal for turning off the power supply in the case of a runaway, and a pulse output section for outputting a pulse to the protection means based on a signal from the main control section. It is characterized in that it is determined that the software is operating normally when there is a pulse input of a fixed period from the pulse output unit.

  The power supply control system of the present invention is a system for controlling a power supply relay by software. The power on / off control in this power control system is performed by the control means.

  The power supply control system of the present invention includes the main control unit, the protection unit, and the pulse output unit as described above, and the protection unit has a pulse input of a constant period from the pulse output unit, Judge that the software is operating normally. Note that the fixed-cycle pulse output from the pulse output unit is output based on the signal from the main control unit. If the main control unit is operating normally, a fixed-cycle pulse is always output. However, when an abnormality occurs in the operation of the main control unit (that is, when the software runs out of control), the pulse output is interrupted.

  In other words, the protection means always monitors software runaway in the control means, and when the pulse input from the pulse output section is interrupted, it is determined that the software has runaway, and the power supply for turning off the power supply. Output a control signal.

  Thus, the power supply control system of the present invention monitors whether the software is operating normally by the protection means judging whether or not the pulse output unit outputs pulses at a constant cycle. Is. According to the above configuration, it is possible to always monitor software runaway, not only when turning off the power without operating the main control unit wastefully, and when software runaway occurs, The power can be forcibly turned off.

  The power supply control system of the present invention does not use a counter as in the prior art, but detects a software abnormality based on the presence or absence of a pulse input. Therefore, the time until the abnormality is detected (counter time) ) Can be obtained in advance.

  In the power supply control system of the present invention, the pulse output unit, when the main control unit is in an operating state, is controlled by the main control unit and outputs a pulse with a fixed period to the protection means, When the main control unit is in a standby state, the main control unit preferably includes an automatic pulse output unit that automatically outputs a pulse having a fixed period to the protection means.

  According to the above configuration, when the main control unit enters a standby state, the automatic pulse output unit outputs a pulse to the protection means instead of the input / output port unit controlled by the main control unit. There is no need to return the unit from the standby state. Therefore, unnecessary power consumption can be eliminated. That is, since it is not necessary to return the main control unit to detect software runaway as in Patent Document 2, it is possible to suppress power consumption.

  In the power supply control system of the present invention, the protection means compares the voltage applied by the input pulse with a reference voltage, and outputs a power supply control signal when the voltage applied by the input pulse exceeds the reference voltage. It is preferable to have a comparison part.

  According to the above configuration, when the software runs out of control and cannot output a pulse with a fixed period to the protection means, the voltage on the input pulse side in the voltage comparison unit continues to rise and exceeds the reference voltage. At this time, since the power supply control signal for turning off the power is output from the voltage comparison unit, the power can be forcibly turned off.

  In the power supply control system of the present invention, it is preferable that the constants of the components constituting the circuit connected to the input terminal on the input pulse side of the voltage comparison unit are determined by the cycle of the input pulse.

  The length of one cycle of the pulse input to the protection means is changed depending on the processing speed of the hardware that operates the software and the contents of the software. When the pulse period changes, the time required for the voltage on the input pulse side detected by the voltage comparison unit to exceed the reference voltage is different. However, the time required to exceed the reference voltage has a great influence on the time from when the software runs away to when the power is turned off, so it is preferable to always keep the time constant.

  According to the above configuration, even when the pulse period changes in this way, the constants of the components constituting the circuit connected to the input terminal on the input pulse side without changing the circuit configuration inside the protection means In other words, the time required for the input pulse voltage to exceed the reference voltage is fixed by simply changing the resistance value of the resistor connected to the input terminal on the input pulse side and / or changing the capacitance of the capacitor. Can be kept in.

  In the power supply control system of the present invention, it is preferable that the reference voltage is changed according to a cycle of an input pulse.

  The time required for the voltage on the input pulse side to exceed the reference voltage is preferably kept constant as described above. Therefore, when the period of the input pulse changes, the time required for the input pulse voltage to exceed the reference voltage is made constant by performing the simple operation of changing the reference voltage as described above. Can keep.

  In the power supply control system of the present invention, the automatic pulse output unit stops the pulse output when an external interrupt signal for returning the main control unit to the operating state is input, and the input / output port unit It is preferable to start pulse output under the control of the main control unit after the control unit returns to the operating state.

  According to the above configuration, when the main control unit returns from the standby state, the automatic pulse output unit is not controlled by the main control unit, but an external interrupt signal is directly input to the automatic pulse output unit. Stop pulse output. On the other hand, the input / output port section starts pulse output under the control of the main control section. Thus, by stopping the automatic pulse output without going through the main control unit, it is possible to monitor whether the software is running out of control when the main control unit returns from the standby state.

  As described above, the power control system according to the present invention includes a main control unit serving as the core of power control, a protection unit that outputs a power control signal for turning off the power when software runs out of control, and the main control unit. And a pulse output unit that outputs a pulse to the protection means based on a signal from the device, and the protection means operates normally when there is a pulse input of a certain period from the pulse output unit. It is characterized by judging that it is.

  Therefore, according to the above configuration, it is possible to always monitor software runaway not only when turning off the power without operating the main control unit wastefully, but when software runaway occurs. Has the effect that the power supply can be forcibly turned off.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 5 as follows. The present invention is not limited to this description.

  In the present embodiment, a power control system provided in a digital multi-function peripheral having functions such as a copying machine, a printer, a FAX, and a scanner will be described as an example. FIG. 2 shows a schematic configuration of the power supply control system according to the present embodiment.

  The power supply control system according to the present embodiment includes a software control switch SW2 that constitutes a switch portion, and a controller unit (control means) 10 that controls the software control switch SW2 by software. The controller unit 10 is provided inside a main body system 100 such as a digital multifunction peripheral.

  As shown in FIG. 2, in the main system 100, in addition to the software control switch SW2 controlled by software, an external switch SW1 for manually turning on / off the power is also provided in parallel with SW2. Each switch can be turned on and off. When SW <b> 1 or SW <b> 2 is turned on, AC 100 V power is supplied to the main system 100 via the power supply unit 30.

  The software control switch SW2 normally turns on the software control switch SW2 by software processing when there is a fax transmission reservation or data backup operation to the HDD even when the external power supply SW1 is turned off. When there is a FAX transmission reservation, the controller unit is kept in a standby state for energy saving until the reservation time, and when the reservation time is reached, the operation state is restored by a timer interrupt (interrupt means 20). When the FAX transmission reservation or the backup operation to the HDD is completed, SW2 is turned off by software processing.

  Next, the internal configuration of the control means of the power supply control system will be described with reference to FIG. As shown in FIG. 1, the controller unit 10 includes a CPU (main control unit) 1 serving as a core of power control, a chip set 2 that is a system controller, a ROM 4 that stores various programs, RAM 3 functioning as a memory, HDD (hard disk drive) 5, input / output port (pulse output unit, input / output port unit) 6 for inputting / outputting signals under the control of the CPU 1, automatically outputting pulses under predetermined settings An automatic pulse output circuit (automatic pulse output unit) 7 is connected to the CPU 1 through a bus line. In addition to this, inside the controller unit 10, a hard protect circuit (protection means) 8 that outputs a hard protect signal (power control signal) HP for turning off the power when the software runs out of control, and an input / output An OR circuit 9 for providing a power switch ON / OFF signal (ON / OFF) output from the port 6 and the hard protect signal is provided.

  The power supply control system according to the present embodiment has the above-described configuration, so that, for example, when there is a fax transmission reservation, the soft control switch SW2 is kept on even when the external switch SW1 is off. I can keep it. In other words, the main body system is provided with such a power supply control system, so that, for example, even if the external switch SW1 is turned off at night when the function of the copying machine or the like is not used, the setting is made in the software. If this is done, the power can be turned on until the FAX transmission reservation time.

  In addition, if the software control switch is set to turn off after a certain time elapses after the FAX transmission is finished, the power can be automatically turned off.

  However, in such a system where the power switch is controlled by software, when the software runs out of control while waiting for fax transmission, during transmission, or after fax transmission ends (that is, when the software stops operating normally) In addition, there is a risk that the soft control switch SW2 cannot be turned off and the power is kept on.

  Therefore, in the power supply control system according to the present embodiment, it is determined that the software has gone out of control when the pulse input of a certain period indicating that the CPU 1 is operating normally is interrupted, and the software control switch SW2 Is provided with a hard protect circuit 8 for outputting a hard protect signal (HP) for turning off.

  In addition, as a pulse output unit 11 that functions to input pulses of a fixed period to the hard protect circuit 8, when the CPU 1 is in an operating state, an input / output that is controlled by the CPU and outputs a CPU control pulse (Pulse 1). A port (input / output port unit) 6 and an automatic pulse output circuit (automatic pulse output unit) 7 that automatically outputs a pulse having a fixed period when the CPU 1 is in a standby state are provided. The automatic pulse output circuit 7 outputs an automatic output pulse (Pulse 2) when the high level of the enable signal (EN) set by the CPU 1 to the input / output port 6 is input before the CPU 1 enters the standby state. To start.

  On the other hand, for example, when an instruction for operating the main system is input to the input unit which is one of the interrupting means 20, an interrupt signal is input to the CPU 1 and the automatic pulse output circuit 7. With this interrupt signal, the CPU 1 returns to the operating state, and the automatic pulse output circuit 7 stops outputting the automatic output pulse. When the CPU 1 returns to the operating state, the input / output port is controlled and the input / output port starts outputting the CPU control pulse (Pulse 1).

  That is, the automatic pulse output circuit 7 stops the pulse output when an interrupt signal for returning the CPU to the operating state is input from the outside, and the input / output port 6 is controlled by the CPU 1 that has returned to the operating state to control the pulse. As the output is started, the automatic pulse output circuit 7 and the input / output port 6 alternately output pulses having a constant cycle.

  In the hard protect circuit 8, the CPU control pulse (Pulse 1) output from the input / output port 6 or the automatic output pulse (Pulse 2) output from the automatic pulse output circuit 7 has a pulse input of a certain period, so that the software Judge that the wearer is operating normally. When the pulse input from the input / output port 6 or the automatic pulse output circuit 7 is interrupted, it is determined that the software has run out of control, and a hard protect signal (OFF) is sent to the OR circuit 9 to turn off the power. HP) is output. The OR circuit 9 receives the hard protect signal (HP) and outputs a soft control switch signal (SSW) for turning off the power to the soft control switch SW2.

  If the software is operating normally, the OR circuit 9 receives a power ON / OFF signal (ON / OFF) from the input / output port 6 according to an instruction from the CPU 1. Entered. As a result, the OR circuit 9 outputs a soft control switch signal (SSW) for turning the power on or off.

  As described above, in the power supply control system of the present embodiment, when the CPU 1 is in the standby state, the automatic pulse output circuit 7 pulses the hard protect circuit 8 instead of the input / output port 6 controlled by the CPU 1. Therefore, it is not necessary to return the CPU 1 from the standby state in order to monitor the operation of the software. Therefore, it is possible to always monitor the runaway of software without causing the CPU 1 to operate wastefully and causing unnecessary power consumption.

Next, the internal configuration of the automatic pulse output circuit 7 will be described with reference to FIG.
The automatic pulse output circuit 7 is a circuit that works when the CPU 1 is in a standby state (sleep state). As shown in FIG. 3, a latch circuit 71 and an enable pulse generation circuit 72 are provided inside the automatic pulse output circuit 7. The latch circuit 71 receives an enable signal (EN) indicating that the CPU 1 is in a standby state, a reset signal (RE) for initializing the circuit, and the interrupt signal (INT) described above. Input portions of the reset signal (RE) and the interrupt signal (INT) are connected to the latch circuit 72 via the AND circuit 73. In the latch circuit 71, when the enable signal (EN) becomes “High”, the output becomes “High” and is input to the enable pulse generation circuit 72. At this time, the enable pulse generation circuit 72 outputs an automatic output pulse.

  When an interrupt signal (INT) for instructing the CPU 1 to enter the operating state is input to the latch circuit 71, the output of the latch circuit 72 becomes “Low” and is input to the enable pulse generation circuit 72. At this time, the enable pulse generation circuit 72 stops the output of the automatic output pulse.

  FIG. 5 shows pulse output timings of various signals output from each circuit in the power supply control system according to the present embodiment. The various signals shown in FIG. 5 are (a) a reset signal, (b) a system clock signal, (c) an enable signal, (d) an interrupt signal, (e) an automatic output pulse, and (f) a CPU control pulse. The system clock signal (b) is a reference clock for synchronizing the entire system.

  In FIG. 5, first, at the time t1, in the state where the CPU 1 is operating, (a) the reset signal becomes “High” (that is, the system is released from the reset state and can operate normally). ). At this time, the CPU control pulse output from the input / output port 6 is input to the hard protect circuit 8, and the hard protect circuit 8 is operated normally by the presence of a pulse input of a fixed period by the CPU control pulse. Judge that you are doing.

  Next, at time t2, the CPU 1 switches from the operating state to the standby state (sleep state). As a result, the output of the (f) CPU control pulse output from the input / output port 6 stops. At this time, (c) an enable signal (EN) is output from the input / output port 6 according to an instruction from the CPU 1 and input to the automatic pulse output circuit 7. That is, the enable signal is in a “High” state. Then, the automatic pulse output circuit 7 starts outputting the (e) automatic output pulse having the same cycle as the CPU control pulse.

  Therefore, even when the CPU 1 switches from the operating state to the standby state, a pulse having a constant cycle is always input to the hard protect circuit 8. As a result, the hard protect circuit 8 can determine that the software operates normally and that the operation state of the CPU 1 has been switched normally.

  After that, when the CPU 1 is in a standby state, when FAX transmission or FAX reception is performed, automatic pulse output is performed from an input unit for performing FAX transmission operation or interrupt means such as a FAX reception unit. (D) An interrupt signal is input to the circuit and the CPU 1 (at time t3 in FIG. 5). Then, (c) the enable signal is switched from “High” to “Low”, and the automatic pulse output circuit 7 (e) stops outputting the automatic output pulse. On the other hand, when the interrupt signal is input to the CPU 1, the CPU 1 is in an operating state. Therefore, if the switching of the operating state is performed normally (that is, if the software is operating normally), the input / output port 6 It is controlled by the CPU 1 and starts outputting the (f) CPU control pulse with a fixed period again.

  As described above, in the power supply control system according to the present embodiment, as long as the software of the controller unit 10 is operating normally, the hardware can be used regardless of whether the CPU 1 is in an operating state or in a standby state. A pulse having a constant period is always input to the protect circuit 8. Thereby, the hard protect circuit 8 can determine that the software is operating normally.

  If the software runs away due to a software bug or the like, the input / output port cannot be controlled, and the pulse output from the input / output port 6 or the automatic pulse output circuit 7 stops. .

  Then, the hard protect circuit 8 determines that the software has gone out of control by stopping the pulse input at a fixed period, and outputs a hard protect signal (HP) for turning off the software control switch SW2.

  As described above, according to the power supply control system of the present embodiment, when the CPU 1 is switched from the standby state to the operating state by the interrupt signal, the interrupt signal is also directly input to the automatic pulse output circuit 7. Since the pulse output from the automatic pulse output circuit 7 can be stopped without going through the CPU 1, it is possible to more reliably detect that the software is running out of control when the CPU 1 returns from the standby state.

  Next, a method for determining the software operating state from the presence or absence of pulse input in the hard protect circuit 8 will be described. FIG. 4 shows an example of the circuit configuration inside the hard protect circuit 8.

  As shown in FIG. 4, the hard protect circuit 8 includes a voltage applied from the CPU control pulse (Pulse 1) or automatic output pulse (Pulse 2) side (collectively, a “voltage applied by the input pulse”), Alternatively, it is referred to as “voltage at point A” and a reference voltage, and a comparator (voltage comparator) that outputs a hard protect signal (HP) when the voltage applied by the input pulse exceeds the reference voltage Vs. ) 81 is provided.

  Here, the configuration of the circuit connected to the input terminal on the input pulse side in the comparator 81 will be described. The input terminal to which Pulse 1 or Pulse 2 is input and the input terminal on the input pulse side (that is, point A) in the comparator 81 are connected via a transistor Q1.

  An input terminal to which Pulse1 or Pulse2 is input is connected to the base of the transistor Q1, and a resistor R1, a capacitor C1, a diode D1, and a resistor R2 are disposed therebetween.

  The input terminal on the input pulse side is connected to the collector of the transistor Q1, and a resistor R4 is disposed therebetween. Also, the input terminal on the input pulse side is connected to a resistor R4, a resistor R5 connected to a power source, and a grounded capacitor C1.

  The emitter of the transistor Q1 is grounded. The base and emitter of the transistor Q1 are connected via a resistor R3.

  In the hard protect circuit 8 having the above circuit configuration, the input voltage at the point A does not exceed the reference voltage Vs if the CPU control pulse (Pulse 1) or the automatic output pulse (Pulse 2) is input at a constant cycle. Is set to

Here, the relationship between the voltage fluctuation at point A and the input pulse will be described with reference to FIG.
As shown in FIG. 6, when the CPU control pulse or the automatic output pulse is input at a constant cycle, the voltage at the point A drops to 0 every time one cycle of the pulse elapses. ing.

  Specifically, when the transistor Q1 is in the OFF state (period B in the graph of FIG. 6), the electric charge is accumulated in the capacitor C2, so that the voltage value at the point A increases. Then, when the transistor Q1 is turned on (point C in the graph of FIG. 6), the charge escapes to GND, so that the voltage value falls to zero. According to the configuration of the hard protect circuit 8 described above, the transistor Q1 is instantaneously turned on at the time when the input pulse has just passed for one cycle. This is because a current flows through the capacitor C1 only momentarily, and the voltage at the base of the transistor Q1 momentarily goes high (transistor Q1 on) and then goes low (transistor Q1 off).

  In other words, in the circuit composed of the resistors R1, R2, R3, the capacitor C1, the diode D1, etc. on the base side of the transistor Q1, each constant is set so that the transistor Q1 is turned on when an input pulse has passed for one cycle. Is set.

  When the software runs away (period D in the graph of FIG. 6), the pulse input is interrupted, so that the transistor Q1 is not turned on and the voltage value at the point A continues to rise. When the voltage value at the point A exceeds the reference voltage Vs, the comparator 81 becomes “High” and a hard protect signal (HP) is output.

  As described above, according to the configuration of the hard protect circuit 8 described above, when the pulse is input at a constant period, the voltage at the point A is discharged before it becomes the reference voltage and falls to 0. When the pulse stops due to runaway (that is, when the waveform is fixed to the high level or the low level), the reference voltage is reached without being discharged. Then, the output of the comparator 81 is inverted and the hard protect signal becomes active. As a result, a soft control switch signal for forcibly turning off the power is output, and the soft control switch can be forcibly turned off.

  By the way, the length of one cycle of the CPU control pulse output by the control of the CPU 1 varies depending on the processing speed of the hardware that operates the software and the contents of the software. If this pulse period changes, the time required for the voltage of the input pulse detected by the comparator 81 to exceed the reference voltage will differ.

  For example, when the pulse period is shortened, the input pulse passes for one period while the voltage at the point A is relatively low, the transistor Q1 is instantaneously turned on, and the voltage drops to zero. Therefore, when the software runs away in a system with a short pulse period, the time required to exceed the reference voltage Vs becomes longer than usual, and as a result, it is delayed to detect that the software has runaway.

  However, according to the configuration of the hard protect circuit 8 in the present embodiment, the degree of increase in voltage at the point A (that is, the slope in the graph shown in FIG. 6) is changed by changing the value of the resistor R5 or the capacitance of the capacitor C2. ) Can be changed. Therefore, even in systems with different pulse periods, the time required to detect that the software has gone out of control can be easily made constant.

  Further, when the period of the input pulse changes, the time required to detect that the software has run out of control can be made constant by changing the value of the reference voltage Vs. The change of the reference voltage Vs can be easily performed by changing a potential or a resistance value connected to the reference voltage, as conventionally performed.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  That is, in the present embodiment, the power supply control system provided in the digital multifunction peripheral has been described as an example. However, the present invention is not limited to this, and includes a power supply system controlled by software. It can be applied to all electronic devices and systems.

  INDUSTRIAL APPLICABILITY The present invention can be used for any electronic device provided with a power supply control system in which power on / off is controlled by software, and can reliably turn off power when the software runs away.

It is a block diagram which shows the structure of the power supply control system concerning this Embodiment. It is a schematic diagram which shows schematic structure of the power supply control system concerning this Embodiment. It is a schematic diagram which shows the internal structure of the automatic pulse output circuit with which the power supply control system shown in FIG. 1 was equipped. FIG. 2 is a circuit diagram showing an internal configuration of a hard protect circuit provided in the power supply control system shown in FIG. 1. It is a timing chart which shows the pulse output timing of the signal output from each structure in a power supply control system. 6 is a graph showing a relationship between a pulse waveform output from a pulse output unit and a voltage [V] at a point A of the hard protect circuit shown in FIG. 4.

Explanation of symbols

1 CPU (main control unit)
6 I / O port (pulse output, I / O port)
7 Automatic pulse output circuit (automatic pulse output unit)
8 Hard protection circuit (protection means)
81 Comparator (Voltage comparison unit)

Claims (6)

A power control system for controlling a power switch,
Control means for controlling the switch of the power supply by software, and interrupt means,
It said control means includes a main controller at the core of the power supply control, and protection means for outputting a power control signal for the software is turned off the power when runaway pulse of a constant period to said protection means A pulse output unit for performing output,
The protective means determines that the software is operating properly if from the pulse output unit is an input of the pulse, it is determined that the software runs away when the input of the pulse is stopped Output the above power control signal,
The pulse output unit includes an input / output port unit and an automatic pulse output unit,
The interrupt means, when returning the main control unit from the standby state to the operating state, transmits an interrupt signal for the return to the main control unit and does not pass through the main control unit. The signal is also sent to the automatic pulse output unit,
When the interrupt signal is input, the main control unit returns from the standby state to the operation state, does not output the pulse from the input / output port unit in the standby state, and does not output the pulse in the operation state. The above pulse is output from the unit,
The automatic pulse output unit outputs the pulse in the standby state and stops outputting the pulse when the interrupt signal is input . The main control unit is configured to shift from the operation state to the standby state after outputting an enable signal indicating that the standby state is to be entered from the input / output port unit.
The enable signal output from the input / output port unit is input to the automatic pulse output unit,
The power supply control system according to claim 1, wherein the automatic pulse output unit starts outputting the pulse when the enable signal is input from the input / output port unit . It said protection means, the voltage comparison inputs the pulse, compares the voltage with a reference voltage applied by the pulse, and outputs the power control signal when the voltage applied by the pulse exceeds the reference voltage power control system according to claim 1 or 2, characterized in that have a part.   4. The power supply control system according to claim 3, wherein constants of components constituting a circuit connected to an input terminal on the input pulse side of the voltage comparison unit are determined by a cycle of input pulses.   The power supply control system according to claim 3, wherein the reference voltage is changed according to a cycle of an input pulse. A multifunction machine comprising the power supply control system according to any one of claims 1 to 5.

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