JP2001350526A - Power saving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power saving circuit which saves standby-time power consumption without greatly lowering the source voltage supplied to a constant voltage circuit nor stopping the operation of a control circuit supplied with the electric power from the constant voltage circuit even if a main power circuit is actuated by turning on a relay switch. SOLUTION: A standby transformer 2 is provided with two output terminals 2a and 2b, the output terminal for supplying electric power to the relay switch 7 and the output terminal for supplying electric power to the constant voltage circuit 5 are made independent of each other, and the voltage at the output terminal 2b which supplies the electric power to the constant voltage circuit 5 is suppressed low to reduce the power consumption in standby mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power saving circuit for suppressing power consumption during standby of a device.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing an example of a conventional power saving circuit. In FIG. 4, 1 is an AC power supply and 2 is this A power supply.
A standby transformer connected to the C power supply 1, D1 is a bridge diode for rectifying the output of the secondary terminal of the standby transformer 2, C1 is a capacitor for smoothing the output rectified by the bridge diode D1, and 3 is a switch to be described later. A control circuit for controlling, 4 is a main circuit of the device, 5 is a constant voltage circuit for stabilizing an output smoothed by the capacitor C1 to a constant voltage and supplying the same to the control circuit 3, and 6 is a main power circuit for supplying power to the main circuit 4. And 7, a relay switch including a contact 7a inserted in series with the main power supply circuit 6 and an energizing coil 7b energized by a current on the secondary side of the standby transformer 2. The control circuit 3 opens and closes the contact 7a. Is controlled.

In such a conventional power saving circuit, in order to suppress power consumption during standby of the device, the power is supplied to the control circuit 3 which needs to operate even during standby of the device and the main circuit 4 which does not need to operate. Each power supply circuit is independent. By using the relay switch 7 to turn off the main power supply circuit 6 that supplies power to the main circuit 4 when the device is on standby, current consumption that has been flowing through the main circuit 4 even when the device was on standby can be eliminated. As a result, power consumption during standby of the device can be reduced accordingly.

[0004]

In the conventional power saving circuit as described above, the current flowing through the control circuit 3 is set to be extremely small in order to minimize the power consumption during standby. Therefore, when the control circuit 3 closes the contact 7 a of the relay switch 7 at the time of starting the device, the current flowing from the AC power supply to the main power supply circuit 6 is much larger than the current flowing to the control circuit 3. The output voltage V1 of D1 drops significantly.

A power supply for the control circuit 3 is a bridge diode D.
Since the voltage V1 is supplied from the output 1, when the voltage V1 drops below a certain voltage, the output voltage V2 of the constant voltage circuit 5 also starts to drop, and the control circuit 3 may stop operating. In order not to stop the operation of the control circuit 3, it is necessary to set the output voltage V1 of the bridge diode D1 higher than necessary, and the power consumption in the standby state of the device is increased by the higher voltage. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first object of the present invention is to reduce the voltage of an output terminal that supplies power to a relay switch when starting up a device. This also prevents the voltage at the output terminal supplying power to the constant voltage circuit from being affected.

A second object is to supply a stable voltage to the control circuit even if the voltage of the AC power supply decreases and the voltage of the output terminal of the standby transformer that supplies power to the constant voltage circuit decreases. It was done.

[0008]

A power saving circuit according to the present invention comprises a main circuit, a main power supply circuit connected to an AC power supply for supplying power to the main circuit, and a power supply circuit between the AC power supply and the main power supply circuit. The switch circuit includes an inserted switch circuit, a control circuit for controlling the switch circuit, a constant voltage circuit for supplying a constant voltage to the control circuit, and a standby transformer connected to the AC power supply. And two output terminals for supplying independent power to the constant voltage circuit.

Further, the voltage of the output terminal of the standby transformer connected to the switch circuit is set higher than the voltage of the output terminal connected to the constant voltage circuit.

An auxiliary power supply circuit for detecting a drop in the output voltage of the constant voltage circuit and applying a voltage to the input side of the constant voltage circuit so as to compensate for the voltage drop at the output terminal of the standby transformer connected to the switch circuit. Is provided.

An auxiliary power supply circuit for detecting a drop in the input voltage of the constant voltage circuit and applying a voltage to the input side of the constant voltage circuit so as to compensate for the voltage drop at the output terminal of the standby transformer connected to the switch circuit. Is provided.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a circuit diagram of a power saving circuit according to Embodiment 1 of the present invention. In the figure, 1 is an AC power supply, 2 is a standby transformer having two secondary output terminals 2a and 2b, D2 and D3 are diodes for rectifying the output of the standby transformer 2, C2 and C3 are diodes D2 and D3.
And 3, a control circuit for controlling the operation of the device, for example, a microcomputer. 4 is a main circuit of the device, 5 is a constant voltage circuit that stabilizes the voltage smoothed by the capacitor C3 to a constant voltage and supplies the voltage to the control circuit 3;
Is a relay switch which is a switch circuit including a contact 7a inserted in series with the main power supply circuit 6 and an energizing coil 7b energized by the current of the secondary output terminal 2a of the standby transformer 2. 3 controls the opening and closing of the contact 7a. The voltage of the output terminal 2a is set to be higher than the voltage of the output terminal 2b.

In the power saving circuit configured as described above, when a device is started, a current flows through the energizing coil 7b of the relay switch 7 by a control signal from the control circuit 3 so that the contact 7
When a is closed, a large current flows from the AC power supply 1 through the main power supply circuit 6, so that the output voltage V3 of the diode D2 connected to the output terminal 2a is reduced under the influence. However, since the output terminal 2b of the standby transformer 2 that supplies power to the constant voltage circuit 5 is provided as a lower voltage terminal independently of the output terminal 2a, the output voltage V4 of the diode D3 is almost zero. It does not decrease and has little effect on the output voltage V5 of the constant voltage circuit 5. Therefore, there is no problem even if the output voltage V4 of the diode D3 is set lower than the output voltage V1 of the conventional circuit shown in FIG. 4, and the power consumed by the control circuit 3 during standby can be reduced accordingly.

Embodiment 2 FIG. FIG. 2 shows a circuit diagram of a power saving circuit according to Embodiment 2 of the present invention. As described above, since the voltage supplied to the low-voltage circuit 5 is kept as low as possible, if the voltage of the AC power supply 1 decreases, the output voltage V4 of the standby transformer 2 and the voltage of the constant-voltage circuit 5 The output voltage V5 may decrease and the control circuit 3 may stop operating.

Therefore, in the present embodiment, as shown in FIG. 2, the auxiliary power supply circuit 8 is added to, for example, a diode D2 circuit, and the output voltage V5 of the constant voltage circuit 5 is monitored by the auxiliary power supply circuit 8 to reduce the voltage V5. Is detected, the output voltage V3 is supplied from the auxiliary power supply circuit 8 to the input side of the constant voltage circuit 5 so as to compensate for the decrease, so that the operation of the control circuit 3 is not stopped.

Embodiment 3 FIG. 3 is a circuit diagram of a power saving circuit according to Embodiment 3 of the present invention. In the second embodiment described above, a decrease in the output voltage V5 of the constant voltage circuit 5 is detected. In the present embodiment, the auxiliary power supply circuit 10 that detects a decrease in the input voltage V4 of the constant voltage circuit 5 is provided. And when this detects a drop in voltage V4,
The output voltage V3 is supplied from the auxiliary power supply circuit 10 to the input side of the constant voltage circuit 5, so that the operation of the control circuit 3 is not stopped.

[0017]

As described above, according to the present invention, the output terminal is added to the standby transformer, and a voltage lower than the supply voltage to the switch circuit is supplied to the constant voltage circuit, thereby affecting the operation of the control circuit. It is possible to suppress the power consumption in the standby state without having any effect.

Further, it is possible to obtain a power saving circuit in which the operation of the control circuit does not stop even when the voltage of the AC power supply decreases.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a power saving circuit according to Embodiment 1 of the present invention.

FIG. 2 is a circuit diagram showing a power saving circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a power saving circuit according to Embodiment 3 of the present invention.

FIG. 4 is a circuit diagram showing a conventional power saving circuit.

[Explanation of symbols]

1 AC power supply, 2 Standby transformer, 2a output terminal, 2b output terminal, 3 control circuit, 4 main circuit, 5 constant voltage circuit, 6 main power circuit, 7 relay switch, 7a contact, 7
b Energizing coil, 8 auxiliary power circuit, 10 auxiliary power circuit, D2 diode, D3 diode, C2 capacitor, C3 capacitor.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G066 LA10 5H410 BB04 CC03 DD02 DD05 EA16 EA28 EA37 EB40 FF03 FF24 FF25 LL04 LL18

Claims (4)

[Claims] 1. A main circuit, a main power supply circuit connected to an AC power supply for supplying power to the main circuit, a switch circuit inserted between the AC power supply and the main power supply circuit, and control for controlling the switch circuit. Circuit, a constant voltage circuit for supplying a constant voltage to the control circuit, and a standby transformer connected to the AC power supply. The standby transformer supplies independent power to the switch circuit and the constant voltage circuit. A power-saving circuit comprising two output terminals. 2. The power saving circuit according to claim 1, wherein the voltage of the output terminal of the standby transformer connected to the switch circuit is set higher than the voltage of the output terminal connected to the constant voltage circuit. 3. An auxiliary power supply circuit for detecting a drop in the output voltage of a constant voltage circuit and applying a voltage to the input side of the constant voltage circuit so as to compensate for the voltage drop at the output terminal side of a standby transformer connected to the switch circuit. The power saving circuit according to claim 1 or 2, further comprising: 4. An auxiliary power supply circuit for detecting a drop in an input voltage of a constant voltage circuit at an output terminal side of a standby transformer connected to a switch circuit and applying a voltage to an input side of the constant voltage circuit so as to compensate for the voltage drop. The power saving circuit according to claim 1 or 2, further comprising: