JPH07308065A - Power supply - Google Patents

Abstract

PURPOSE:To make it possible to supply a DC voltage when necessary from the main power supply circuit side to an electronic device by the control from the secondary side by a simple configuration without providing a standby power supply for always outputting to the secondary side by a transformer. CONSTITUTION:A rectifying circuit 5 is used, in which the primary side is DC interrupted from the secondary side by capacitors C4 and C5, at the standby power supply side (b) of the main power supply circuit side (a). By turning on/off a make and break switch SW1, ON/OFF control terminal (H-enable) of IC1 becomes 'H' by a photocoupler PC1 during ON, a switching transistor Q1 performs switching operation, and a DC voltage Vo is output from a rectifying circuit 4 to a DC output terminal 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply unit used in electronic equipment such as copiers, printers and facsimiles.
In particular, it relates to DC supply and stop of a switching power supply that supplies DC power to electronic equipment.

[0002]

2. Description of the Related Art A conventional power supply device of this type is shown in FIG.
The configuration is as shown in the circuit diagram. That is, the AC input to the primary side alternating current (AC) input terminals 1 and 1 on the main power supply circuit side (a) obtains a DC output by the diode bridge 2 including the diodes D1 to D4 and the smoothing capacitor C1. It is supplied to the next-stage AC generation circuit 3. This AC generating circuit 3 includes a phototransistor Tr that constitutes one of the photocouplers PC1, a switching transistor Q1, and an ON / OFF control terminal connected between the emitter of the phototransistor Tr and the base of the switching transistor Q1. (H-enable)
And a transformer T having a primary winding and a secondary winding connected between the collector of the phototransistor Tr and the collector of the switching transistor Q1.
Composed of 1 and.

Then, the switching transistor Q1 starts or stops the switching operation based on the "H" or "L" state of the ON / OFF control terminal of the IC1, and an alternating current is applied to the secondary winding side of the transformer T1. Generate output.

This alternating current output becomes a direct current output in the rectifying circuit 4 consisting of the diode D5 and the smoothing capacitor C2, and the direct current voltage Vo is supplied from the DC output terminals 7, 7 to electronic equipment not shown.

The supply control of the DC voltage Vo to the electronic device is performed as follows. That is, the AC input from the AC input terminals 1 and 1 via the transformer T2 on the standby power supply side (b) is a diode bridge composed of diodes D6 to D9, a current limiting resistor R4, a zener diode ZD1 and a charging diode. It is rectified and charged by the capacitor C3, and the DC output of the constant voltage V1 is always output as the standby power supply voltage. That is, when supplying the DC voltage Vo to the electronic device, the open / close switch SW1 (switching regulator) is closed and the light emitting diode D10 forming the other side of the photocoupler PC1 is caused to emit light. This light emission output is received by the phototransistor Tr to turn on / off the IC1.
The F control terminal becomes "H", the switching operation of the switching transistor Q1 is started, and an AC output is output from the transformer T1 to the rectifier circuit 4. in this case,
The charging capacitor C3 is charged through the diode D11, the direct current continues to flow to the resistor R2, and the power-on state is maintained.

Next, when the open / close switch SW1 is opened, the light from the light emitting diode D10 is not received by the phototransistor Tr and the ON / OFF control terminal of the IC1 is "L".
Then, the switching operation of the switching transistor Q1 is stopped, and the AC output from the transformer T1 is cut off. In this way, the open / close switch S on the standby power supply side (b)
The output of the DC voltage Vo to the DC output terminals 7, 7 is controlled on the output side of the rectifier circuit 4 on the main power supply circuit side (a) by the opening / closing operation of W1.

[0007]

However, in the circuit configuration of the conventional power supply device described above, in order to supply the DC voltage Vo from the main power supply circuit side (a) to the electronic equipment, the open / close switch S is used.
A standby power source that constantly outputs to the secondary side of the transformer T2 for turning on / off by W1 is required, and the cost is increased because the transformer T2 is included.

The present invention solves such a problem and does not require a standby power supply which constantly outputs to the secondary side with a simple structure. An object is to provide a power supply device capable of supplying a DC voltage.

[0009]

In order to achieve the above-mentioned object, the first means is a rectifying means for obtaining a DC output on the secondary side and an AC on the primary side input to the rectifying means. An insulation means provided between the primary side and the second side.
It is characterized in that the secondary side is cut off by direct current and insulated.

The second means includes a first rectifying means for rectifying an AC input on the primary side, an AC generating means for obtaining an AC output by using the DC output of the first rectifying means as an input, and the AC means. Second rectifying means for receiving a direct current output on the secondary side by using the alternating current output of the generating means, third rectifying means for obtaining a direct current output by receiving the alternating current input on the primary side, and the third rectifying means. And an insulating means provided between the primary side AC input terminal and an AC generation control means for controlling the operation of the AC generating means by a switch means for turning on / off the DC output of the third rectifying means. It is characterized by having.

Further, the third means has, in addition to the second means, a transmission means for supplying the DC output of the second rectifying means to the secondary side of the third rectifying means. And

[0012]

According to the first means of the present invention, the AC of the rectifying means is
Since the insulating means for blocking DC is provided on the input side, the primary side and the secondary side of the rectifying means can be DC blocked and separated.

According to the second and third means, since the first means is used as the standby power supply of the main power supply circuit, it is not necessary to construct the standby power supply which constantly outputs to the secondary side.
The standby power supply can have an inexpensive configuration that does not require a transformer.

According to the third means, the DC voltage Vo
The standby voltage (constant voltage) V1 can be electrically separated and used.

[0015]

1 is a circuit diagram showing the configuration of a power supply device according to a first embodiment of the present invention. In FIG. 1, 1 and 1 are AC input terminals on the primary side (A), 5 is a rectifier circuit composed of bridge diodes D6 to D9 on the secondary side (B), C3 is a charging capacitor for rectified output, and rectified The circuit 5 and the charging capacitor C3 form a rectifying means. Reference numerals 6 and 6 are direct current (DC) output terminals of the rectifying means, and C4 and C5 are capacitors provided between the AC input terminals 1 and 1 and the input side of the rectifying circuit 5 as an insulating means for blocking direct current. Is.

Since this embodiment is configured as described above, the AC input from the AC input terminals 1 and 1 is full-wave rectified by the rectifier circuit 5 through the capacitors C4 and C5, and the charging capacitor C3. The DC output smoothed to a constant voltage is supplied from the DC output terminals 6 and 6 as a DC voltage of an electronic device (not shown).

In this way, the primary side (A) and the secondary side (B) can be isolated and insulated by blocking the direct current with the capacitors C4 and C5.

Next, FIG. 2 is a circuit diagram showing the configuration of a power supply device according to a second embodiment of the present invention, which is the same as that shown in FIG.
It is another power supply device using the circuit of the power supply device of. That is, as shown in FIG. 2, the main power supply circuit side (a) and the standby power supply side (b)
The AC input side of the standby power source side (b) is connected to the AC input terminals 1, 1 of the main power source circuit side (a).
In addition, the same components as those in FIGS. 1 and 4 are designated by the same reference numerals, and the description thereof will be omitted.

Here, the rectifying circuit 2 and the smoothing capacitor C
1 is the first rectifying means, rectifying circuit 4 and smoothing capacitor C2
Is the second rectifying means, the rectifying circuit 5 and the Zener diode Z
D1 and the charging capacitor C3 are the third rectifying means, the open / close switch SW1 and the photocoupler PC1 are the AC generating control means, and the diode D11 and the resistor R3 are the DC output of the second rectifying means of the third rectifying means. It is a transmission means for supplying to the next side.

Next, showing concrete numerical examples of each component on the standby power source side (b), the capacitors C4 and C5 are 0.01 μF and 250
V ceramic capacitor, bridge diodes D6 to D9 are 200V, 0.5A commercial frequency diode, Zener diode ZD1 is Vz16V, 0.5W, charging capacitor C3 is 220μF, 25V aluminum electrolytic capacitor, resistor R2 is 10kΩ, 1 / It is 4W.

The operation of this embodiment configured as described above will be described.

When AC is input to the primary side (A), it is full-wave rectified by the rectifier circuit 2 on the main power supply circuit side (a) and smoothed by the smoothing capacitor C1. It is applied to the 3 side. In this case, IC1 of AC generator 3
Since the ON / OFF control terminal of the switch is "L", the switching transistor Q1 is in the non-operation state and does not start the switching operation, and the DC voltage Vo of the main power supply circuit side (a) is
Is also 0V.

At this time, AC is input from the AC input terminals 1 and 1 via the capacitors C4 and C5 on the standby power source side (b), full-wave rectified by the rectifying circuit 5 to charge the charging capacitor C3, and V1 is generated and continues to rise, but the voltage is clamped and maintained at 16V by the Zener diode (Vz = 16V) ZD1.

In the above state, the standby power source side (b)
When the open / close switch SW1 of is turned on, a direct current flows through the light emitting diode D10 of the photocoupler PC1 through the resistor R2, the phototransistor Tr of the photocoupler PC1 is turned on, and the ON / OFF control terminal of IC1 is set to "H", The switching operation of the switching transistor Q1 is started. As a result, the AC input through the transformer T1 is rectified by the rectifier circuit 4, and the DC voltage Vo (12V)
At the DC output terminals 7, 7.

The DC voltage Vo is applied to the DC output terminals 7, 7
Then, the charging capacitor C3 is charged through the diode D11, the direct current continues to flow to the resistor R2, and the power-on state is maintained.

Next, when the open / close switch SW1 is turned off,
The direct current to the light emitting diode D10 of the photocoupler PC1 becomes 0, the phototransistor Tr of the photocoupler PC1 turns off, the ON / OFF control terminal of the IC1 becomes “L”, and the switching operation of the switching transistor Q1 stops. The DC voltage Vo on the power supply circuit side (a) is 0 V, that is, it is turned off.

As described above, in this embodiment, by using the standby power source in which the primary side and the secondary side are cut off from the direct current, the direct current of the main power source circuit side can be used, and it is always output to the secondary side as in the prior art. The configuration of the standby power supply is not required and the circuit configuration is simplified.

FIG. 3 is a circuit diagram showing the configuration of a power supply device according to a third embodiment of the present invention. This is a third DC output of the second rectifying means by the diode D11 and the resistor R3 shown in FIG. This is a power supply device in which the transmission means for supplying to the secondary side of the rectification means is deleted and the DC voltages V0 and V1 are separated. This power supply device is used when the output of the DC voltage V0 on the main power supply side (a) and the output of the DC voltage V1 on the standby power supply side (b) are used separately.

[0029]

As described above, in the power supply device of the present invention, a DC blocking capacitor is arranged on the input side of the circuit for rectifying AC to DC, so that the primary side and the secondary side of the rectifying circuit are arranged. And an inexpensive power supply device can be configured.

Further, the power supply device of the present invention uses the first power supply device (FIG. 1) as a standby power supply together with the main power supply circuit, so that the standby power supply is always output to the secondary side by the transformer as in the conventional case. It is not necessary to take the configuration, the transformer can be omitted, and the circuit configuration can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a power supply device according to a first embodiment of the present invention.

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

FIG. 3 is a circuit diagram showing a configuration of a power supply device according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a conventional power supply device having a main power supply circuit and a standby power supply circuit.

[Explanation of symbols]

1 ... AC input terminal, 2,4,5 ... rectifier circuit, 3 ... AC generator, 6, 7 ... DC output terminal, D ₁ to D _9, D
₁₁ ... diodes, D ₁₀ ... light-emitting diodes, C _1, C ₂ ...
Smoothing capacitor, C ₃ ... Charging capacitor, C ₄ ,
C ₅ ... a coupling capacitor, ZD1 ... Zener diode, PC1 ... photo coupler, Tr ... phototransistor, Q1 ... switching transistors, SW1 ... close switch, (A) ... 1 primary, (B) ... 2 primary, ( a) ...
Main power supply circuit side, (b)… Standby power supply side.

Claims (4)

[Claims] 1. A rectifying means for obtaining a DC output on the secondary side, and an insulating means provided between an AC input on the primary side input to the rectifying means. A power supply device characterized in that the secondary side is insulated from the direct current. 2. The power supply device according to claim 1, wherein the insulating means is composed of a capacitor. 3. A first rectifying means for rectifying an AC input on the primary side, an AC generating means for obtaining an AC output by using a DC output of the first rectifying means as an input, and an AC output of the AC generating means. Second rectifying means for obtaining a DC output on the secondary side as an input, third rectifying means for obtaining a DC output by receiving the AC input on the primary side as input, the third rectifying means and the primary side An insulating means provided between the AC input terminals;
AC power generation control means for controlling the operation of the alternating current generation means by a switch means for turning on / off the direct current output of the rectification means. 4. A first rectifying means for rectifying an AC input on the primary side, an AC generating means for obtaining an AC output by using a DC output of the first rectifying means as an input, and an AC output of the AC generating means. Second rectifying means for obtaining a DC output on the secondary side as an input, third rectifying means for obtaining a DC output by receiving the AC input on the primary side as input, the third rectifying means and the primary side An insulating means provided between the AC input terminals;
The alternating current generation control means for controlling the operation of the alternating current generating means by the switch means for turning on / off the direct current output of the rectifying means, and the direct current output of the second rectifying means are supplied to the secondary side of the third rectifying means. A power supply device comprising a transmission means.