JP2001245470A - Power source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source which has a simple structure contriving a power saving and can be commonly used among different types of equipment. SOLUTION: In a standby state, as a current to be supplied to IPS (information processing system) and the like is so small and a voltage drop at a detective resistance 40 is small, a transistor 38 does not turn on and a phototransistor 36B does not turn on. Therefore an ON/OFF terminal of control circuit 52 is input by a voltage at a high level so that a control signal to be output to a MOS-FET50 is turned off, and a power supply to a motor and the like is interrupted. When a FAX directive signal or the like is detected, an energy consumption increases as a IPS or the like is actuated for forming an image and a voltage drop at a detective 40 becomes large. The transistor 38 is turned on as the voltage drop on the detective resistance 40 becomes large. With this the phototransistor 36B is turned on and the ON/OFF terminal of the control circuit 52 is input by a voltage at a low level, the control signal output to the MOS-FET50 is started and the power supply is resumed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a power supply device,
In particular, it relates to a power supply device used for an electrophotographic printer or copier.

[0002]

2. Description of the Related Art For example, in an image forming apparatus such as an electrophotographic copying machine, a facsimile, a printer, etc., a liquid crystal display for displaying an operation state, an operation panel, and an apparatus for forming an image (for example, a charging device, a photosensitive member, Light beam scanning device,
And a power supply (for example, a switching power supply) for supplying power thereto.

In the above-described image forming apparatus, a power supply for supplying power to each section of the apparatus is divided into a main power supply and a sub power supply according to the magnitude of the supplied power, for example, as shown in FIG. It has become normal.

As shown in FIG. 5, a main power supply rotates a load required during a normal operation (at the time of image formation), for example, a motor for rotating a photosensitive member or a polygon mirror included in a light beam scanning device. The power is supplied to a motor or the like for driving. On the other hand, the sub power supply is, for example, an IPS (Image Pr
ocessing System: a circuit that detects the load required during normal operation of a hard disk, etc., the load required during standby other than during normal operation of an LED, fan, liquid crystal display, etc., and a FAX instruction signal, a print instruction signal, etc. Is supplied to a control circuit or the like including

In such a power supply device, at the time of the standby, the control circuit monitors an external FAX instruction signal or the like, and when the FAX instruction signal or the like has not been received for a predetermined time or more, an OFF signal is sent to the main power supply. By sending the power, the main power is turned off, and unnecessary power consumption is suppressed.

For example, Japanese Patent Application Laid-Open No. Hei 7-248738 discloses a method for judging whether or not there is a change in the displayed video content.
A device for turning off a main power supply when there is no change in video content is described.

Further, Japanese Patent Application Laid-Open No. 8-95431 discloses that
A power supply device of a normal load such as a display unit is separated from a power supply device (main power supply) such as a motor having a standby state, and power is supplied to the power supply device such as a motor when a copy start switch is operated, thereby saving power. A device for powering is described.

Further, Japanese Patent Application Laid-Open No. 9-134,096 discloses a drive system power supply circuit (main power supply) for generating a drive voltage required only during image formation and a control system power supply circuit for generating a minimum required voltage during standby. There is described an apparatus for saving power by stopping a drive system power supply circuit required only during image formation during standby.

[0009]

However, each of the above prior arts has a function of transmitting an on / off signal for turning on / off the main power supply and a function of detecting an external signal as a condition for transmitting the on / off signal. A control circuit is required, which increases the cost. Further, since this control circuit is unique to the device, it must be created for each model, and it is difficult to share the power supply device between different models.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and provides a power supply device capable of saving power with a simple configuration and sharing a device between different models. The purpose is to do.

[0011]

In order to achieve the above object, the invention according to claim 1 comprises a first device section which operates in a normal operation mode, a device which operates in a standby operation mode, and a normal device which operates by a drive input signal. A second device unit including a device that operates in an operation mode; and a power supply device that supplies power to a target device including: a main power supply that supplies power to the first device unit; An auxiliary power supply for supplying power;
The power supply system further includes a detection unit that detects a power supply state of the sub power supply, and a control unit that turns on and off the main power supply based on a detection result of the detection unit.

The target device includes a first device unit that operates in a normal operation mode, and a second device unit including a device that operates in a standby operation mode and a device that operates in a normal operation mode based on a drive input signal. . An example of such a target device is an image forming device. In such a power supply device that supplies power to the target device, the main power supply supplies power to the first device unit that operates only in the normal operation mode. When the apparatus is a facsimile, a printer, a copying machine, or the like, the first device section includes, for example, a polygon mirror included in a light beam scanning device for forming a latent image corresponding to an image on a photosensitive member, or the photosensitive device. A drive system device such as a motor for rotating a body or the like is included.

The auxiliary power supply supplies power to a second device section including a device operating in a standby operation mode and a device operating in a normal operation mode based on a drive input signal. The drive input signal is, for example, a drive instruction signal for instructing the drive of the target device, for example, a FAX instruction signal, a print instruction signal,
Timer signals and the like are included.

Further, as the second device section, for example, IPS
During normal operation of the (image processing system) and the hard disk, that is, at the time of standby other than during the normal operation of the load necessary for image formation, and at the time of normal operation of the LED, the fan, the liquid crystal display, the detection circuit for detecting the FAX instruction signal and the print instruction signal, etc. The equipment of the control system such as necessary load is included.

The detecting means detects a power supply state of the sub power supply. From this power supply state, it can be determined whether or not the operation mode is the normal operation mode. That is, when the power supply is large, the drive input signal is input and the second device unit operates to determine that the image is in the image forming state, that is, the normal operation mode. It can be determined that the operation of the two device units has stopped and the operation mode is the standby operation mode.

Therefore, the control means turns on and off the main power supply based on the detection result of the detection means. That is, for example, when it is detected from the detection result that the operation mode is the normal operation mode, the main power supply is turned on and the power supply to the first device is started. The main power supply is turned off to stop the power supply to the first device unit.
As a result, useless power consumption in the standby state can be suppressed.

Also, a function of transmitting an on / off signal for turning on / off the main power supply for turning on / off the main power supply based on a power supply state of the sub power supply, and a function of detecting an external signal as a condition for transmitting the on / off signal Since a special control circuit or the like having such a configuration is not required, the cost can be reduced, and power supply to the control circuit is not required.
Further, power saving can be achieved. In addition, the independence from other devices can be enhanced, and the power supply device can be shared between different models. Therefore, design becomes easy and short-term development becomes possible.

According to a second aspect of the present invention, the detecting means includes:
Detecting an operation state of the second device based on a value corresponding to the power supply from the sub power source, and the control unit turns on the main power when detecting operation of the second device, The main power supply is turned off when the stop of the second device section is detected.

The detecting means detects an operating state of the second device based on a value corresponding to a power supply state from the sub power supply.
When the second device section is operating, it can be determined that the power consumption is normal and the operation mode is the normal operation mode. When the second device section is stopped, the power consumption is low and the standby operation is performed. Mode can be determined.

Therefore, the control means turns on the main power supply when detecting the operation of the second device section, starts power supply to the first device section, and when detecting the stop of the second device section. Turns off the main power supply and stops the power supply to the first device unit.
As a result, useless power consumption in the standby state can be suppressed.

The operating state of the second device section can be detected by the voltage or current supplied from the sub power supply.

Therefore, the detecting means detects a voltage corresponding to the power supply state of the sub power supply as the operation state of the second device section,
The control means may turn on the main power supply when the detected voltage becomes equal to or higher than a predetermined value, and turn off the main power supply when the detected voltage becomes lower than the predetermined value.

The operating state of the second device section can be detected by detecting a voltage corresponding to the power supply state as described above. This voltage can be detected by using, for example, a resistor or a current transformer. it can.

When the detected voltage is equal to or higher than a predetermined value, that is, a voltage at which the second device can be operated, the second device consumes power, for example, for image formation. Since it can be determined that the operation mode is the normal operation mode, the main power supply is turned on and the supply of power to the first device section is started. On the other hand, when the voltage becomes smaller than the predetermined value, the second device section does not consume much power, and it can be determined that the second device section is in the standby operation mode. Stop supplying power to the unit.

As a result, wasteful power consumption in the standby state can be suppressed, and a special control circuit for transmitting an on / off signal to the main power supply becomes unnecessary, so that the cost can be suppressed. This makes it possible to increase the independence of the power supply device from other devices, and to share the power supply device between different models.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to the drawings. First,
An outline of the present invention will be described with reference to FIG.

As shown in FIG. 1, a power supply 10 includes a main power supply 12 as a main power supply and a sub power supply 1 as a sub power supply.
The main power supply 12 is operated at the time of steady operation (at the time of image formation) as the first device unit 11 as shown in FIG.
For example, power is supplied to a load required for the operation, for example, a motor for rotating the photosensitive member, a motor for rotating a polygon mirror included in the light beam scanning device, and the like.

On the other hand, the sub power source 14 serves as a drive input signal 15 for driving an LED, a fan, a liquid crystal display, and an image forming apparatus necessary for a normal operation as the second device section 13 such as an IPS or a hard disk. F
Power is supplied to a load required during standby other than during normal operation, such as a signal detection circuit for detecting an AX instruction signal or a print instruction signal.

Here, when the signal detection circuit detects a signal for canceling the standby state, such as a FAX instruction signal or a print instruction signal, during standby, the IPS necessary for the image formation is detected.
Also, the amount of power consumed by the hard disk to perform an operation for image formation increases. As a result, the amount of power supplied from the sub power supply 14 increases.

When the detecting means 17 detects that a power equal to or more than a predetermined value is supplied from the sub power supply 14 to the IPS, the hard disk or the like, the switching means 19 turns on the main power supply 12. Thus, the supply of electric power from the main power supply 12 to the motor and the like is started.

Conversely, when the image forming process is completed, the power detected by the load detecting means in the sub power supply 14 becomes equal to or less than a predetermined value, and the switch means in the main power supply 12 is turned off. As a result, the power supply from the main power supply 12 is stopped, and the operation returns to the standby state.

Next, a specific circuit configuration of the power supply device 10 will be described with reference to FIG.

The sub power supply 14 of the power supply 10 shown in FIG.
Has a transformer 16. One end of the primary winding 18 of the transformer 16 is connected to the input smoothing circuit 22,
The other end is connected to the drain terminal of the MOS-FET 24. The gate terminal of the MOS-FET 24 is connected to the control circuit 26.
Are connected, and the source terminal is connected to the input smoothing circuit 22.

The input smoothing circuit 22 is connected to an AC power supply 28. The input smoothing circuit 22 includes, for example, a diode and a capacitor, rectifies and smoothes the AC power supplied from the AC power supply 28, and supplies the DC power to the primary winding 18 of the transformer 16.

When a control signal is input from the control circuit 26 to the gate terminal of the MOS-FET 24, the DC voltage applied to the primary winding 18 of the transformer 16 is switched. Thus, an AC voltage corresponding to the winding ratio is induced on the secondary winding 20 side of the transformer 16.

One end of the secondary winding 20 is connected to the anode terminal of the diode 30. The cathode terminal of the diode 30 is connected to one end of a resistor 32, one end of a capacitor 34,
It is connected to an IPS or a hard disk, which is a load required in a normal operation, and a fan, an LED, a liquid crystal display, etc., which are loads required in a standby state. Thus, the AC voltage induced in the secondary winding 20 is rectified and smoothed by the diode 30 and the capacitor 34 and supplied to the IPS, the hard disk, the fan, the LED, the liquid crystal display and the like as a DC voltage.

The control circuit 26 detects an output voltage and monitors the detection signal from a detection circuit (not shown) that outputs a detection signal corresponding to the detected output voltage so that the output voltage becomes the target voltage. Then, the duty ratio of the control signal is feedback-controlled.

The other end of the resistor 32 is connected to the anode terminal of the light emitting diode 36A of the photocoupler 36. The cathode terminal of the light emitting diode 36A is connected to the collector terminal of the NPN transistor 38. The base terminal of the transistor 38 is connected to the other end of the secondary winding 20 and one end of a detection resistor 40 as detection means. The other end of the detection resistor 40 is connected to the other end of the capacitor 34 and is grounded.

On the other hand, the main power supply 12 has a transformer 42. One end of the primary winding 44A of the transformer 42 is
The other end is connected to the MOS-F
The drain terminal of ET50 is connected. MOS-F
The control circuit 52 is connected to the gate terminal of the ET 50, and the source terminal is connected to the input smoothing circuit 48.

The input smoothing circuit 48 is connected to the AC power supply 28. The input smoothing circuit 48 includes, for example, a diode and a capacitor, rectifies and smoothes the AC power supplied from the AC power supply 28, and supplies the DC power to the primary winding 44A of the transformer 42.

When a control signal is input from the OUT terminal of the control circuit 52 to the gate terminal of the MOS-FET 50, the DC voltage applied to the primary winding 44A of the transformer 42 is switched. As a result, an AC voltage corresponding to the turn ratio is induced on the secondary winding 46 side of the transformer 42.

One end of the secondary winding 46 is connected to the anode terminal of the diode 54. The cathode terminal of the diode 54 is connected to one end of a capacitor 56, a motor or the like, which is a load required during normal operation. The other end of the secondary winding 46 is connected to the other end of the capacitor 56 and is grounded. As a result, the AC voltage induced in the secondary winding 46 is applied to the diode 54 and the capacitor 56.
And supplied as a DC voltage to the motor and the like.

The control circuit 52 detects an output voltage, monitors the detection signal from a detection circuit (not shown) that outputs a detection signal corresponding to the detected output voltage, and adjusts the output voltage to a target voltage. Then, the duty ratio of the control signal is feedback-controlled.

On the other hand, one end of the primary winding 44B of the transformer 42 is connected to the anode terminal of the diode 58, and the other end is connected to the phototransistor 3 of the photocoupler 36.
6B and the GND terminal of the control circuit 52. The cathode terminal of the diode 58 is connected to one end of the resistor 60 and to the Vcc terminal of the control circuit 52. The other end of the resistor 60 is connected to the collector terminal of the phototransistor 36B and to the ON / OFF terminal of the control circuit 52.

The transistor 38 and the photocoupler 3
6 and the control circuit 52 correspond to the control means of the present invention.

Next, the operation of the first embodiment will be described.

When a control signal that repeats on and off at predetermined intervals is output to the gate terminal of the MOS-FET 24 by the control circuit 26, energy is stored in the primary winding 18 of the transformer 16 and the secondary winding 20 of the transformer 16 is stored. , A secondary winding voltage is generated.

The AC voltage induced on the secondary winding 20 side is rectified and smoothed by the diode 30 and the capacitor 34 and output as a DC voltage.

Here, in the case of the standby state, the IPS
And the load current supplied to the hard disk is small,
The current flowing through the detection resistor 40 is also small. That is, since the voltage drop due to the detection resistor 40 is small, the transistor 38
Does not turn on, the light emitting diode 36A of the photocoupler 36
No current flows through Therefore, since the phototransistor 36B on the main power supply 12 side is not conducting, a high level is input to the ON / OFF terminal of the control circuit 52.

In the control circuit 52, when a high level is input to the ON / OFF terminal, M is output from the OUT terminal.
The control signal output to the OS-FET 50 is turned off. As a result, the supply of power from the main power supply 12 to the motor or the like is cut off.

When the signal detection circuit detects a signal for canceling the standby state such as a FAX instruction signal or a print instruction signal from the outside, the IPS or the hard disk required for the image formation performs an operation for image formation. The amount of power consumed increases. As a result, the amount of power supplied from the sub power supply 14 increases.

That is, the load current increases and the detection resistor 4
The current flowing through 0 also increases. Therefore, the voltage drop due to the detection resistor 40 increases, and the transistor 38 turns on. Thereby, the light emitting diode 3 of the photocoupler 36 is
A current flows through 6A, the phototransistor 36B on the main power supply 12 side conducts, and a low level is input to the ON / OFF terminal of the control circuit 52.

In the control circuit 52, when a low level is inputted to the ON / OFF terminal, the MOS-FE is inputted from the OUT terminal.
Output of the control signal to T50 is started. As a result, energy is stored in the primary winding 44A of the transformer 42,
A secondary winding voltage is generated in the secondary winding 46 of the transformer 42, and the AC voltage induced on the secondary winding 46 side is rectified and smoothed by the diode 54 and the capacitor 56, and is converted into a DC voltage for a motor or the like. Is output.

The timing for turning on the transistor 38 can be changed, for example, by changing the resistance value of the detection resistor 40.

As described above, since the activation of the main power supply 12 is automatically turned on / off according to the magnitude of the current flowing through the resistor 40, that is, the magnitude of the power supplied from the sub power supply 14, the main power supply is turned on / off. A special control circuit having a function of transmitting an ON / OFF signal for detecting the ON / OFF signal and a function of detecting an external signal as a condition for transmitting the ON / OFF signal is not required, so that costs can be reduced, and power supply to the control circuit can be suppressed. Is also unnecessary, so that further power saving can be achieved. Further, since the control circuit is not required, independence from other devices can be increased, and it is possible to share a power supply device between different models. Therefore, design becomes easy and short-term development becomes possible.

[Second Embodiment] Next, a second embodiment of the present invention will be described. In the second embodiment, a modified example of the power supply device 10 described in the first embodiment will be described. The same parts as those of power supply device 10 shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The power supply device 10 ′ shown in FIG.
A primary winding 62A of a current transformer 62 as a detecting means is connected between the other end of the zero and the capacitor 34. A resistor 64 is connected to the secondary winding 62B of the current transformer 62. One end of the secondary winding 62B is grounded, and the other end is connected to an anode terminal of a diode 66 and one end of a capacitor 68 whose other end is grounded.

The cathode terminal of the diode 66 is connected to a resistor 7
0 is connected to one end, and the other end of the resistor 70 is connected to a resistor 72.
And the base terminal of the transistor 74. The other end of the resistor 72 and the emitter terminal of the transistor 74 are connected to the other end of the secondary winding 44B, the other end of the capacitor 76, and the GND terminal of the control circuit 52.
One end of the capacitor 76 is connected to the cathode terminal of the diode 58, one end of the resistor 60, and the Vcc terminal of the control circuit 52. The collector terminal of the transistor 74
The ON / OFF terminal of the control circuit 52 and the other end of the resistor 60 are connected.

Next, the operation of the second embodiment will be described.

In the standby state, the voltage of the primary winding 62A of the current transformer 62 is small because the load current supplied to the IPS and the hard disk is small. For this reason,
The voltage induced in the secondary winding 62B is also small, and the transistor 74 does not conduct. Therefore, ON / O of the control circuit 52
A high level is input to the FF terminal.

In the control circuit 52, when a high level is input to the ON / OFF terminal, M is output from the OUT terminal.
The control signal output to the OS-FET 50 is turned off. As a result, the supply of power from the main power supply 12 to the motor or the like is cut off.

When the signal detection circuit detects a signal for canceling a standby state such as a FAX instruction signal or a print instruction signal from the outside, the IPS or the hard disk required for the image formation performs an operation for image formation. The amount of power consumed increases. As a result, the amount of power supplied from the sub power supply 14 increases.

That is, the load current increases, and the current flowing through the primary winding 62A of the current transformer 62 also increases. Therefore, the voltage of the primary winding 62A increases, and the voltage induced in the secondary winding 62B also increases, so that the transistor 74 conducts. As a result, the control circuit 52
A low level is input to the N / OFF terminal.

In the control circuit 52, when a low level is inputted to the ON / OFF terminal, the MOS-FE is inputted from the OUT terminal.
Output of the control signal to T50 is started. As a result, energy is stored in the primary winding 44A of the transformer 42,
A secondary winding voltage is generated in the secondary winding 46 of the transformer 42, and the AC voltage induced on the secondary winding 46 side is rectified and smoothed by the diode 54 and the capacitor 56, and is converted into a DC voltage for a motor or the like. Is output.

As described above, since the activation of the main power supply 12 is automatically turned on / off in accordance with the magnitude of the voltage applied to the current transformer 62, that is, the magnitude of the power supplied from the sub power supply 14, the main power supply is turned on / off. A special control circuit having a function of transmitting an on / off signal for detecting the on / off signal and a function of detecting an external signal as a condition for transmitting the on / off signal becomes unnecessary, and the cost can be suppressed, and the power supply to the control circuit can be suppressed. Since supply is not required, power saving can be further achieved. Further, since the control circuit is not required, independence from other devices can be increased, and it is possible to share a power supply device between different models. Therefore, design becomes easy and short-term development becomes possible.

[Third Embodiment] Next, a third embodiment of the present invention will be described. In the third embodiment, a modified example of the power supply device 10 described in the second embodiment will be described. The same parts as those of power supply device 10 shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The power supply 10 ″ shown in FIG.
Between the source terminal of the ET 24 and the input smoothing circuit 22, a primary winding 80A of a current transformer 80 having a resistor connected in parallel is connected. One end of the secondary winding 80B of the current transformer 80 is connected to the OCP terminal of the control circuit 26 via a diode, one end of the capacitor 82, and the cathode terminal of the Zener diode 84, and the other end is connected to the GND terminal of the control circuit 26. And the other end of the capacitor 82. One end of a resistor 86 is connected to the anode terminal of the Zener diode 84, and the other end of the resistor 86 is connected to the anode terminal of the light emitting diode 36A of the photocoupler 36.

Next, the operation of the third embodiment will be described.

In the standby state, since the load current supplied to the IPS and the hard disk is small, the voltage applied to the primary winding 80A of the current transformer 80 is small. For this reason, the voltage induced in the secondary winding 80B is also small, and the Zener diode 84 does not conduct. Therefore, no current flows through the light emitting diode 36A of the photocoupler 36, and the phototransistor 36B on the main power supply 12 side does not conduct, so that a high level is input to the ON / OFF terminal of the control circuit 52.

In the control circuit 52, when a high level is input to the ON / OFF terminal, M is output from the OUT terminal.
The control signal output to the OS-FET 50 is turned off. As a result, the supply of power from the main power supply 12 to the motor or the like is cut off.

When the signal detection circuit detects a signal for canceling the standby state such as a FAX instruction signal or a print instruction signal from the outside, the IPS or hard disk required for the image formation performs an operation for image formation. The amount of power consumed increases. As a result, the amount of power supplied from the sub power supply 14 increases.

That is, the load current increases, and the current flowing through the primary winding 80A of the current transformer 80 also increases. Therefore, the voltage applied to the primary winding 80A increases and the voltage induced in the secondary winding 80B also increases, so that the Zener diode 84 conducts. This allows
A current flows through the light emitting diode 36A of the photocoupler 36, the phototransistor 36B on the side of the main power supply 12 is turned on, and a low level is input to the ON / OFF terminal of the control circuit 52.

In the control circuit 52, when a low level is inputted to the ON / OFF terminal, the MOS-FE is inputted from the OUT terminal.
Output of the control signal to T50 is started. As a result, energy is stored in the primary winding 44A of the transformer 42,
A secondary winding voltage is generated in the secondary winding 46 of the transformer 42, and the AC voltage induced on the secondary winding 46 side is rectified and smoothed by the diode 54 and the capacitor 56, and is converted into a DC voltage for a motor or the like. Is output.

As described above, since the activation of the main power supply 12 is automatically turned on / off in accordance with the magnitude of the voltage applied to the current transformer 80, that is, the magnitude of the electric power supplied from the sub power supply 14, the main power supply is turned on / off. A special control circuit having a function of transmitting an on / off signal for detecting the on / off signal and a function of detecting an external signal as a condition for transmitting the on / off signal becomes unnecessary, and the cost can be suppressed, and the power supply to the control circuit can be suppressed. Since supply is not required, power saving can be further achieved. Further, since the control circuit is not required, independence from other devices can be increased, and it is possible to share a power supply device between different models. Therefore, design becomes easy and short-term development becomes possible.

[0075]

As described above, according to the present invention,
Since the control unit turns on and off the main power supply based on the power supply state of the sub power supply, a special control circuit or the like is not required, cost can be suppressed, and independence from other devices can be increased. This has the effect that the power supply device can be shared between models.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an outline of the present invention.

FIG. 2 is a circuit diagram of a power supply device according to the first embodiment.

FIG. 3 is a circuit diagram of a power supply device according to a second embodiment.

FIG. 4 is a circuit diagram of a power supply device according to a third embodiment.

FIG. 5 is a schematic diagram for explaining a conventional power supply device.

[Explanation of symbols]

 Reference Signs List 10 power supply device 12 main power supply 14 sub power supply 16, 42 transformer 22, 48 input smoothing circuit 24, 50 MOS-FET 26, 52 control circuit 36 photocoupler 38 transistor 40 detection resistor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06F 1/32 H02J 1/00 307C 5H730 H02J 1/00 307 H04N 1/00 C 9A001 H04N 1/00 G06F 1 / 00332B F-term (reference) 2C061 AP03 AP04 AQ06 HH11 HK11 HT02 2H027 DA01 EA16 EJ17 FA25 ZA01 ZA07 5B011 DB02 DB11 EA10 KK12 LL01 LL06 5C062 AA02 AA05 AB40 AB51 AB53 DA07 GA07 DA02 KA05 LA07 MA10 5H730 AA14 AA16 AS13 AS23 BB43 BB57 BB82 CC01 DD04 EE07 EE73 FD51 FF19 FG01 VV03 XC07 9A001 BB06 JJ35 KK31 KK42

Claims (2)

[Claims] 1. A target device comprising: a first device unit that operates in a normal operation mode; and a second device unit including a device that operates in a standby operation mode and a device that operates in a normal operation mode based on a drive input signal. A power supply device for supplying power to the first device, a main power supply for supplying power to the first device, a sub-power supply for supplying power to the second device, and detection means for detecting a power supply state of the sub-power supply. And a control unit for turning on and off the main power supply based on a detection result of the detection unit. 2. The apparatus according to claim 1, wherein the detecting unit detects an operation state of the second device based on a value corresponding to a power supply from the sub power source, and the control unit detects an operation of the second device. The power supply device according to claim 1, wherein the main power supply is turned on at the time, and the main power supply is turned off when the stop of the second device section is detected.