JP2000138881A - Electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an electronic equipment to surely cope with sudden change in the power supply voltage in the case of the electronic equipment provided with at least two power supply circuit systems, consisting of a power supply circuit for a control system and a power supply circuit for a circuit system other than the control system. SOLUTION: This electronic equipment is provided with a 1st power supply circuit 33, that uses power obtained by a power supply input section for a 1st DC low-voltage power, a 2nd power supply circuit 42 that uses power obtained by the power supply input section for a 2nd DC low-voltage power, monitor means 36, 37 that monitor the 1st DC low-voltage power obtained by the 1st power supply circuit 33, and a control means 21 that is operated by the 2nd DC low-voltage power and initializes circuits 12-17 operated by the 1st DC low-voltage power, when the monitor means 36, 37 detect a fault of the DC low-voltage power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic apparatus having a power supply circuit for converting a power supply such as an AC power supply into a DC low voltage power supply, and more particularly to an electronic apparatus suitable for an apparatus having a standby mode such as a television receiver. .

[0002]

2. Description of the Related Art Conventionally, an electronic device which operates by inputting a commercial AC power supply such as 100 V has a power supply input unit having a structure as shown in FIG. That is, the input unit connected to the power supply line from which the commercial AC power supply 1 is obtained is connected to the diode bridge 3 via the power switch SW0,
This diode bridge 3 converts the current to DC. Then, the power rectified by the diode bridge 3 is supplied to the switching power supply circuit 4. Here, the switching power supply circuit 4
A primary-side capacitor C1 is connected between the power supply and the diode bridge 3. The switching power supply circuit 4 is a circuit configured by an element for switching power supply at a high frequency such as a switching transistor and a control circuit thereof, and for obtaining a DC low-voltage power supply on the secondary side.

The switching power supply circuit 4 shown in FIG.
A circuit for obtaining three types of DC low-voltage power supplies, wherein a first DC low-voltage power supply is supplied to a first circuit 5, a second DC low-voltage power supply is supplied to a second circuit 6, and a third DC low-voltage power supply is provided. Is supplied to the control circuit 7. Here, a capacitor for smoothing the output DC low-voltage power supply is connected to the secondary side of the switching power supply circuit 4. That is, the switching power supply circuit 4
A capacitor C2 is connected between the switching power supply circuit 4 and the second circuit 6, and a capacitor C3 is connected between the switching power supply circuit 4 and the second circuit 6. The capacitor C4 is connected to the circuit 7. The first and the first generated by the switching power supply circuit 4
The second and third DC low-voltage power supplies have power supply values required by the circuits 5, 6, and 7, and may be power supplies having different voltage values or power supplies having the same voltage value.

The voltage of the third DC low-voltage power supply supplied to the control circuit 7 is monitored by a voltage monitoring circuit 8, and data of the voltage value detected by the voltage monitoring circuit 8 is transmitted to the control circuit 7.
Is always determined. When the control circuit 7 determines that the voltage value detected by the voltage monitoring circuit 8 is in an abnormal state lower than the specified voltage value, the operations of the first and second circuits 5 and 6 are performed. It is configured to take measures against a power failure, such as by stopping.

The control circuit 7 has a configuration capable of controlling the first and second circuits 5 and 6 via the bus line 9.
The signal processing in the first and second circuits 5 and 6 is executed based on the control from the control circuit 7. For example, when the device is in the operating state, the mode terminal (terminal indicated as mode in FIG. 3) of the switching power supply circuit 4 is set to the operating side, and when the device is set in the standby state, the mode terminal is set to the standby side. The control circuit 7 is always operating so that it can return from the standby state to the operating state.

As described above, since the control circuit 7 is operated even in the standby state, the switching power supply circuit 4 is always operated in this device even in the standby state. Examples of the electronic device having such a standby mode include a television receiver and a video tape recording / reproducing device (V
TR) exists. That is, these devices are generally configured so that they can be remotely controlled by a remote control signal (such as an infrared signal) from a remote control device, so that on / off control can be performed by remote control. And a control circuit 7 and a remote control signal receiving unit (light receiving unit)
Is configured to always operate. However, when the power switch SW0 is turned off, the operation of this device is completely stopped.

[0007]

By the way, as shown in FIG. 3, there is a configuration in which one switching power supply circuit creates a DC power supply for a control circuit and a DC power supply for other circuits. The device only needs to include one switching power supply circuit, and the configuration of the device is simple. However, it is not preferable from the viewpoint of power consumption of the device. That is, in the standby state, only the control circuit and its peripheral circuits operate, and the power supply is in a light load state with low power consumption. However, the switching power supply circuit itself operates in the same manner as the operation state, and the useless power supply is unnecessary. Since power is also supplied to the load circuit, reduction of power consumption in the standby state is limited.

In order to solve this problem, the device may be provided with two power supply circuits, a power supply circuit for a control circuit and a power supply circuit for other circuits. However, there is a problem that simply providing two sets of power supply circuits cannot cope with an abnormality in the input AC power supply. That is, for example, in the case of a conventional device having only one switching power supply circuit shown in FIG. 3, since there is only one set of power supply circuits, there is a temporary drop in the input AC power supply voltage, for example. When the power supply voltage supplied to the first and second circuits 5 and 6 decreases, the power supply voltage supplied to the control circuit also decreases. This is because the power circuit is 1
In the case of only the set, the power supplied from the secondary side of the power supply circuit to each circuit is to use the capacitor C1 on the primary side in common (that is, when the capacitor C1 is completely discharged, 2 The power supply voltage on the secondary side drops.) Therefore,
The abnormality of the power supplied to the first and second circuits 5 and 6 can be reliably determined from the abnormality of the voltage value detected by the voltage monitoring circuit 8, and the control circuit 7 can correctly deal with the abnormal voltage.

However, in the case of a device provided with two power supply circuits, a power supply circuit for a control circuit and a power supply circuit for other circuits, the charging / discharging time constant of a capacitor provided in the power supply circuit for the control circuit. It is impossible to keep the same charge / discharge time constant of the capacitors included in the power supply circuits for the other circuits, and it is not sufficient to monitor only the power supplied to the control circuit. That is, depending on the capacity of the capacitor connected to the power supply circuit, only the power supplied to the circuits other than the control circuit temporarily decreases, and the power supplied to the control circuit may not fluctuate. In such a case, in the circuit that actually performs the signal processing, the power supply temporarily drops and the signal processing cannot be continued even though the control circuit determines that there is no abnormality. There is a high possibility that it will be in a state. For example, in the case of a television receiver, if the power supply voltage temporarily drops, the data of the channel received by the tuner or the data of the volume adjusted by the audio circuit will be lost, and the receiver will malfunction. Resulting in.

Since the charging / discharging time constant of the power supply circuit is determined by the capacity of the smoothing capacitor and the load impedance, the power supply circuit for the control circuit and the power supply circuit for the other circuits have two power supply circuits. Cannot be set to the same state. In particular, in the case of a power supply circuit corresponding to an AC power supply input having a plurality of voltage values (for example, a power supply circuit corresponding to an AC power supply input in a range of 110 V to 240 V), the charging / discharging time constant of the power supply circuit is large depending on the power supply voltage. Therefore, it is impossible to equalize the characteristics of the two power supply circuits.

An object of the present invention is to make it possible to reliably cope with a sudden change in power supply voltage when at least two power supply circuits are provided, that is, a power supply circuit for a control system and a power supply circuit for other circuits. It is in.

[0012]

According to the present invention, there is provided an electronic apparatus comprising: a first power supply circuit using a power supply obtained at a power supply input section as a first DC low-voltage power supply; and a second power supply circuit obtaining a power supply obtained at a power supply input section. A second power supply circuit serving as a DC low-voltage power supply, monitoring means for monitoring the first DC low-voltage power supply obtained by the first power supply circuit, and a DC low-voltage power supply operated by the second DC low-voltage power supply and monitored by the monitoring means; Control means for initializing a circuit operated by the first DC low-voltage power supply when an abnormality is detected.

According to the electronic apparatus of the present invention, when the output voltage of the first power supply circuit drops instantaneously, this is detected by the control means operating with the power supply of another system, and the original is controlled by the control means. Is performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described.
This will be described with reference to FIGS.

FIG. 1 is a diagram showing a configuration according to the present embodiment. Here, an example is shown in which the invention is applied to an electronic device configured as a television receiver. That is, the antenna 1
The tuner 12 connected to the receiver 1 receives a television broadcast wave of a predetermined channel to obtain a video signal, and supplies the video signal to the selector 13. The video signals obtained at the plurality of external input terminals 14a to 14n are also supplied to the selector 13. The selector 13 selects a predetermined video signal, supplies the selected video signal to the video processing unit 15, and performs various processes required for receiving an image on the video signal.

The video signal processed by the video processing unit 15 is supplied to a matrix circuit 16, and the primary color signals R, G, B
Is performed, and the converted primary color signals R,
G and B are supplied to the drive circuit 17 to be used as signals for driving the cathode ray tube 18, and the electron gun of the cathode ray tube 18 is driven. Further, the synchronization signal component separated from the video signal by the video processing unit 15 is supplied to the deflection system circuit 19 to drive a deflection coil (not shown) of the cathode ray tube 18.

The processing in each circuit constituting the television receiver is executed under the control of a control unit 21 which is a system controller included in the television receiver. The control unit 21
It is configured to send a command to each circuit via the internal bus line 20, and to operate information of operation keys 22 provided in the receiver,
Various controls such as channel selection, input selection, and display mode are performed based on a remote control signal from the remote control device received by the infrared light receiving unit 23. In this case, the control unit 21 includes a memory (for example, a non-volatile memory) that stores the control state of each unit. For example, when the power of the receiver is turned on, the last condition that is the last state stored in this memory is transmitted to the bus line. An initial setting process for setting each unit connected at 20 is performed. In addition, the same initial setting process is performed also at the time of a power failure described later. The last condition set in the initial setting includes, for example, setting of a channel to be received by the tuner 12, setting of an input to be selected by the selector 13, setting of a display mode to be processed by the video processing unit 15, and setting of a volume in the audio processing unit. There are settings. In the configuration shown in FIG. 1, a circuit system for processing an audio signal is omitted.

In the television receiver of the present embodiment, the power is supplied to the control unit 21 and a circuit for supplying power to the peripheral circuits and a circuit for performing image processing from the tuner 12 to the cathode ray tube 18 and the deflection system 19. A separate power supply circuit is provided. That is, this television receiver uses the commercial AC power supply 31 as an input power supply. The commercial AC power supply 31 is, for example, an AC power supply in a range of 110V to 240V. An input unit connected to a power supply line from which the commercial AC power supply 31 is obtained is connected to a power switch SW1.
And the switch SW2 is connected to the diode bridge 32, and the power rectified by the diode bridge 32 is supplied to the first switching power supply circuit 33. The power switch SW1 is a switch for manually turning on the power, and the switch SW2 is a switch controlled by the control unit 21 described later, and is a switch that is turned off when there is no command from the control unit 21. . The first switching power supply circuit 33 is composed of an element for switching the power supply at a high frequency such as a switching transistor, and a control circuit thereof. The first switching power supply circuit 33 corresponds to an input power supply in a range from 110 V to 240 V and has a DC low voltage on the secondary side. This is a circuit for obtaining a power supply, and a relatively large-capacity power supply circuit is used. Between the switching power supply circuit 33 and the diode bridge 32,
The primary side capacitor C11 is connected.

The output on the secondary side of the first switching power supply circuit 33 is the power supply voltage V between terminals 34a and 34b.
_BB is obtained, and the power supply voltage V _CC is obtained between the terminals 35a and 35b. A smoothing capacitor C12 is provided between the first switching power supply circuit 33 and the terminals 34a and 34b.
There Yes connected, this terminal 34a, a voltage of the power source voltage V _BB obtained 34b, it is constituted to be monitored by the voltage monitoring circuit 36. Further, a smoothing capacitor C1 is provided between the first switching power supply circuit 33 and the terminals 35a and 35b.
3 is connected, and the voltage monitoring circuit 37 monitors the voltage of the power supply voltage V _CC obtained at the terminals 35a and 35b. The data of the voltage value monitored (detected) by each of the voltage monitoring circuits 36 and 37 is transmitted to the control unit 21 via the bus line 20. Here, the power supply voltage V _BB is 5 V, and the power supply voltage V _CC is 12 V.

[0020] Then, supply terminal 34a, the power supply voltage V _BB obtained 34b, from the tuner 12 the cathode ray tube 18, of the circuit system that performs receiving processing of up to deflection system 19, to circuits requiring 5V power supply . The power supply voltage V _CC obtained at the terminals 35 a and 35 b is supplied from the tuner 12 to the cathode ray tube 1.
8, one of the circuit systems for performing image reception processing up to the deflection system 19;
Supply 2V power to circuits that require it.

As a circuit for supplying power to the control section 21 and its peripheral circuits, an input section connected to a power supply line from which a commercial AC power supply 31 is obtained is connected to a diode bridge 41 via a power switch SW1. The power rectified by the diode bridge 41 is supplied to the second switching power supply circuit 42. Second switching power supply circuit 42
Is composed of an element for switching the power supply at a high frequency such as a switching transistor, and a control circuit therefor.
Corresponding to an input power supply in the range of 10V to 240V, 2
This is a circuit for obtaining a DC low voltage power supply on the secondary side, and a power supply circuit having a relatively small capacity is used. A primary-side capacitor C is provided between the switching power supply circuit 42 and the diode bridge 41.
21 is connected.

The output of the secondary side of the second switching power supply circuit 42 is a power supply voltage V between terminals 43a and 43b.
_There is a configuration to obtain _AA . A smoothing capacitor C22 is connected between the second switching power supply circuit 42 and the terminals 43a and 43b. The voltage of the power supply voltage V _AA obtained at the terminals 43a and 43b is monitored by a voltage monitoring circuit 44. There is a configuration to do. In this case, the smoothing capacitor C2
The discharge time constant of 1 is larger than the discharge time constant of the smoothing capacitor C11 connected to the primary side of the first switching power supply circuit 33, so that the time until the discharge is extended. The data of the voltage value monitored (detected) by the voltage monitoring circuit 44 is transmitted to the control unit 21. Here, the power supply voltage V _AA is 5 V, and the terminals 43 a and 43 b
Supply voltage V _AA obtained includes a control unit 21, and supplies the infrared receiver 23.

The processing when the power of the television receiver thus configured is turned on will be described. When the user turns on the power switch SW1, the power obtained by rectifying the AC power is supplied to the second switching power circuit 42. Then, the power supply voltage V _AA is obtained at the terminals 43a and 43b on the secondary side of the second switching power supply circuit 42, and the power is supplied to the control unit 21 and its peripheral circuits. With this power supply, the control unit 21 starts operating. At the start of this operation, first, the switch SW2 is controlled to the on state, and the rectified AC power is supplied to the first switching power supply circuit 33, so that the first switching power supply circuit 3
The power of the voltage V _BB and the voltage V _CC output from the power supply 3 is supplied from the tuner 12 to the circuit system for performing image processing from the cathode ray tube 18 to the deflection system 19, and the image receiving process is started in these circuits. You.

At this time, the control unit 21
Supplies initial setting data to each circuit via the control unit 2
First, the last condition stored in the memory 1 is set, and the image receiving state in the last condition is started. After that, the operation of the operation key 22 and the infrared receiving unit 23
When a remote control signal is received at the, control such as channel switching, volume adjustment, and display mode change is performed.
When the control based on the key operation or the remote control signal is performed, the data stored in the memory for storing the last condition in the control unit 21 is updated.

In the receiver of the present embodiment, the control unit 21 constantly determines the power supply voltage detected by each of the voltage monitoring circuits 36, 37, and 44, and performs control based on the determination. The flowchart of FIG.
1 shows a control process performed by the computer. First, immediately after the power is turned on, the television receiver performs an initial setting process for controlling the last condition described above for each circuit (step 101). And after this initial setting is finished,
Based on the operation of the operation key 22 or the reception of a remote control signal by the infrared light receiving unit 23, a steady process for changing the control state is performed (step 102).

In the state where the steady processing is being performed, the control unit 21 determines whether or not the power supply voltage V _BB detected by the voltage monitoring circuit 36 is within a certain range in which the power supply operates normally. Along with step 103), the control unit 21 determines whether or not the power supply voltage V _CC detected by the voltage monitoring circuit 37 is a voltage value within a certain range for normal operation (step 104). When it is determined in each of the determinations that the value is within a certain range, the steady processing in step 102 is continued.

If it is determined in step 103 or 104 that the voltage value is lower than the predetermined range, the process returns to the initial setting process in step 101, and data for setting a last condition in a circuit requiring initial setting is output. Supply. However, when returning from step 103 or 104 to step 101, the switch SW2 is maintained in the on state. Although not shown in the flowchart of FIG. 2, when the voltage monitoring circuit 44 that monitors the power supplied to the control unit 21 detects an abnormality of the power supply voltage V _AA , Execute the setting process.

As described above, according to the television receiver of the present embodiment, a power supply circuit for supplying power to a main circuit system for performing image reception processing and the like as a power supply circuit and a power supply circuit for supplying power to a control system are provided. Since the system is divided into two systems, only the second switching power supply circuit 42 having a small capacity is operated during standby when no image is displayed, so that there is no needless power supply during standby and power consumption during standby is reduced. be able to.

When an abnormal situation occurs such that the voltage of the input AC power supply drops momentarily, the control unit 21
And a smoothing capacitor C22 connected to the switching power supply circuit 42.
Since the control unit 21 has a relatively large discharge time constant, the control unit 21 continues to operate as long as the DC power supply _VAA is continuously supplied to the control unit 21 by the discharge time constant. Therefore, the control unit 21 can cope with an instantaneous fluctuation of the AC power supply.

On the other hand, the DC power supply V output from the switching power supply circuit 33 for supplying power to the main circuit system
_{For BB} and V _CC , one of the switching power supply circuits 33
Since the discharge time constant of the smoothing capacitor C11 connected to the next side is smaller than the discharge time constant of the smoothing capacitor C21 connected to the switching power supply circuit 42,
In an abnormal situation where the voltage of the input AC power supply drops momentarily, the DC power supplies V _BB and V _CC drop momentarily. Therefore, the circuit operated by the DC power supplies V _BB and V _CC is:
A situation in which power is not supplied temporarily may occur, and each circuit may malfunction. Here, in the case of the present embodiment, the power supply voltage drop is caused by the voltage monitoring circuits 36 and 37.
Is determined by the control unit 21 based on the detection of the DC power supplies V _BB and V
_The circuit operated by _CC immediately returns to the original operating state.

For this reason, in order to reduce the power consumption in the standby state, the power supply circuit is configured to have two systems of a power supply circuit for the main circuit system and a power supply circuit for the control system. When the power supply drops momentarily, the control unit immediately judges the abnormality in the power supply circuit for the main circuit system and performs the initial setting, preventing malfunction due to the momentary drop of the input AC power supply. it can.

The discharging time constant of the smoothing capacitor C21 connected to the second switching power supply circuit 42, which is a power supply circuit for the control system, is changed by the first switching power supply circuit 3
3 is larger than the discharge time constant of the smoothing capacitor C11 connected to the second switching power supply circuit 4.
2 is a circuit for supplying power only to the control system, so that a small-capacity power supply is sufficient. Therefore, even if the discharge time constant of the smoothing capacitor C21 is increased, a capacitor having such a large capacity is not required as the capacitor C21. . Further, in the case of this example, since the power supply circuits are completely different for the main circuit system and the control system, the secondary switching power supply circuit The load impedance does not change when viewed from the side. Therefore, it is possible to easily make the discharge time constant of the smoothing capacitor C21 larger than the discharge time constant of the smoothing capacitor C11.

In the above-described embodiment, the power supply circuit for supplying power to the main circuit system is constituted by the first switching power supply circuit 33, but the power supply circuit for supplying power to the main circuit system is Composed of multiple power supply circuits,
The configuration may be such that the voltage on the secondary side of each power supply circuit is monitored. In the above-described embodiment, the switching power supply circuit uses the switching element as the power supply circuit. However, the switching power supply circuit may include another power supply circuit.

In the above-described embodiment, the power supply circuit corresponding to the AC power supply in the range of 110 V to 240 V is used as the input AC power supply. However, the power supply circuit may not be such a power supply circuit corresponding to such a variable voltage. Also, the power supply voltage value may be another voltage value such as 100V. Also,
In the above-described embodiment, the power supply circuit converts a commercial AC power supply to a DC low-voltage power supply. However, a device including another power supply circuit such as a power supply circuit for converting a DC power supply obtained from an automobile battery to a DC low-voltage power supply Also applicable to

Further, in the above-described embodiment, an example in which the present invention is applied to a television receiver has been described. However, the present invention can be applied to various electronic devices in which a power supply needs to be divided between a main circuit system and a control system. it can. For example, the present invention can also be applied to audio equipment such as a stereo reproduction device that reproduces sound from a speaker device by processing an audio signal obtained from an audio signal source (such as a tuner or a disk reproduction device) in an amplifier section.

[0036]

According to the first aspect of the present invention, the first
When the output voltage of the power supply circuit instantaneously drops, this is detected by the control means operated by a power supply of another system, and an initialization process for returning to the original state under the control of the control means is executed. Therefore, even when the power supply circuit is divided between the control means and the other circuits, the power supply abnormality in the actually operating circuit is reliably detected, the operation state is restored, and the instantaneous input power supply voltage Malfunction of the device due to the decrease can be reliably prevented.

According to the second aspect of the present invention, in the first aspect of the present invention, the discharging time constant of the smoothing capacitor provided in the second power supply circuit is reduced by the discharging time constant of the smoothing capacitor provided in the first power supply circuit. By making the time constant larger, the possibility that the power supply voltage supplied to the control means drops even if there is an instantaneous decrease in the input power supply voltage can be reduced. It is more likely that the program will be executed continuously without any problem, and it is possible to quickly cope with a momentary drop in the power supply voltage.

According to a third aspect of the present invention, in the first aspect of the present invention, the second power supply circuit and the control means operated by the second DC low-voltage power supply obtained by the power supply circuit are devices. Operates in the standby mode, and the first power supply circuit and the circuit operated by the first DC low-voltage power supply obtained by the power supply circuit are turned off under the control of the control means when the device is in the standby mode. By setting the state, a device provided with two power supply circuits capable of effectively reducing power consumption during standby can reliably cope with an abnormal input power supply.

According to the invention described in claim 4, in the invention described in claim 3, the circuit that operates with the first DC low-voltage power supply obtained by the first power supply circuit performs processing of a video signal or an audio signal. The initialization is a process of setting a last condition in a circuit for processing a video signal or an audio signal, so that a malfunction when an AC power input is abnormal in the receiver is eliminated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an example of a television receiver according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control processing example according to the embodiment of the present invention;

FIG. 3 is a configuration diagram illustrating an example of a conventional electronic device.

[Explanation of symbols]

12 ... tuner, 13 ... selector, 14 ... video processing unit,
16 matrix circuit, 17 drive circuit, 18 cathode ray tube, 19 deflection system, 20 internal bus line, 21
Control unit 23 23 Infrared signal receiving unit 31 Commercial AC power supply 32 Diode bridge 33 First switching power supply circuit 36 37 Voltage monitoring circuit 41 Diode bridge 42 Second switching power supply circuit,
44: Voltage monitoring circuit, C11, C21: Primary capacitors of switching power supply, C12, C13, C22: Secondary capacitors of switching power supply

Claims (4)

[Claims] 1. A power supply unit, a first power supply circuit that uses a power supply obtained from the power supply input unit as a first DC low-voltage power supply, and a power supply obtained by the power supply input unit is a second DC low-voltage power supply. A second power supply circuit serving as a power supply; monitoring means for monitoring the first DC low-voltage power supply obtained by the first power supply circuit; operating by the second DC low-voltage power supply; An electronic apparatus comprising: a control unit that initializes a circuit that operates with a first DC low-voltage power supply output from the first power supply circuit when a power supply abnormality is detected. 2. The electronic device according to claim 1, wherein a discharge time constant of the smoothing capacitor provided in the second power supply circuit is larger than a discharge time constant of the smoothing capacitor provided in the first power supply circuit. Electronics. 3. The electronic device according to claim 1, wherein said second power supply circuit and a control means operated by a second DC low-voltage power supply obtained by said power supply circuit operate even when the device is in a standby mode. The first power supply circuit and a circuit operated by the first DC low-voltage power supply obtained by the power supply circuit are configured to be turned off under the control of the control unit when the device is in a standby mode. machine. 4. The electronic device according to claim 3, wherein the circuit operated by the first DC low-voltage power supply obtained by the first power supply circuit is a circuit that processes a video signal or an audio signal. The electronic device is a process of setting a last condition in a circuit for processing the video signal or the audio signal.