JP2598868Y2 - Simultaneous input prevention circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simultaneous input prevention circuit, and more particularly, for example, a DC input circuit in which a self-excited RCC circuit and a secondary circuit operated by an AC input are common to the secondary circuit of the self-excited RCC circuit. Excited RCC operated by
Circuit when the AC input has priority (already AC
When the input is given), the primary side circuit of the separately-excited RCC circuit is turned off. When the DC input has priority (when the DC input is already given), the self-excited RCC circuit is turned off.
The present invention relates to a simultaneous input prevention circuit for turning off a primary circuit of a circuit.

[0002]

2. Description of the Related Art In a conventional simultaneous input prevention circuit 1 shown in FIG. 2, a slide shutter 3 is provided in an input terminal section 2 and an AC input terminal 2a or a DC input terminal 2b is closed by the slide shutter 3 to prevent simultaneous input. Was. Also the simultaneous input prevention circuit 1 of a conventional 3, when there is AC input, the base input of the transistor Tr ₁ is detected by the detection circuit 4a, a control signal is input to the control circuit 6a through the photocoupler 5a. Therefore, the PWM control circuit 7 is turned off by the control circuit 6a. On the other hand, when there is a DC input, the operation of the PWM control circuit 9 is detected by the detection circuit 4b, and a control signal is input to the control circuit 6b via the photocoupler 5b. Therefore, the control circuit 6b
As a result, the transistor Tr ₂ becomes conductive, and the transistor T 2
r ₁ is turned off. In this way, simultaneous input has been prevented.

[0003]

In the simultaneous input preventing circuit 1 shown in FIG. 2, when the slide shutter 3 comes off, there is a problem that the circuit 1 is short-circuited by erroneously inputting AC power and DC power. . Further, the simultaneous input prevention circuit 1 shown in FIG. 3 has a problem that the circuit configuration is complicated.

[0004] Therefore, a main object of the present invention is to provide a simultaneous input prevention circuit that can be reliably operated with a simple configuration.

[0005]

SUMMARY OF THE INVENTION The present invention provides an AC power supply.
A self-excited RCC circuit operated by a rectified input, a separately-excited RCC circuit whose secondary side circuit is shared with a secondary side circuit of the self-excited RCC circuit and operates by DC input, and one of a secondary side circuit and a self-excited RCC circuit. Optically coupled to the secondary circuit and D
In a simultaneous input prevention circuit including a photocoupler that operates in response to a C input and absorbs a starting current of a primary circuit of a self-excited RCC circuit, a control winding generating an electromotive force by an AC input, and Of the separately excited RCC circuit
The simultaneous input prevention circuit is characterized by further comprising an off means for turning off a secondary circuit.

[0006]

When the DC input has priority, that is, when the DC input is already
When an input is given, a self-excited R
The phototransistor provided on the primary side of the CC circuit conducts, and the starting current is drawn. Therefore, even if there is an AC input, the self-excited RCC circuit does not operate.

On the other hand, when the AC input has priority, that is, when the AC input is already given, for example, the PWM control circuit is turned off by the induced electromotive force of the control winding. As a result, the separately excited RCC circuit does not operate.

[0008]

According to the present invention, the respective primary circuits are turned off by the photocoupler and the control winding, so that simultaneous input can be reliably prevented with a simple configuration. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

Referring to FIG. 1, a simultaneous input prevention circuit 10 of this embodiment includes an AC input primary circuit 12, a DC input primary circuit 14, and a secondary circuit 16. A primary winding 18 is provided in the AC input side primary circuit 12, and a positive voltage obtained by rectifying an AC voltage is applied to a terminal 20 provided at one end thereof.
Rectified AC voltage to a terminal 22 provided at the other end.
Is applied. The other end of the primary winding 18 the collector of the transistor Tr ₁ is connected, the transistor Tr ₁
Are connected to the terminal 22. A resistor R ₁ , a diode D ₁ and a drive winding 24 are connected in series to the base of the transistor Tr ₁ , and the other end of the drive winding 24 is connected to the emitter of the transistor Tr ₁ .
Further, the starting resistor R ₂ is interposed between one end of the transistor Tr ₁ in the base and the primary winding 18. Furthermore, each connected emitter and collector of the transistor Tr ₂ is the base and emitter of the transistor Tr _1, and a phototransistor Tr ₃ included in the transistor Tr ₂ and the photo-coupler 26 is Darlington connected. Furthermore, in and between the phototransistor Tr ₃ of one end of the emitter and the drive winding 24 and the collector of the phototransistor Tr ₃ of the emitter and the transistor Tr _2, and capacitor C ₁ and diode D ₂ are each interposed I have.

A primary winding 28 is connected to the DC input side primary circuit 14.
Is provided, and a DC voltage is input from a terminal 30 connected to this one end. The other end of the primary winding 28 is connected to the collector of a transistor Tr ₄ whose emitter is grounded, and the PWM control circuit 32 is connected to the base of the transistor Tr ₄ . Also the PWM control circuit 32, is connected to the transistor Tr ₅ of grounded emitter conduction by the base input, the base resistor R _3, the Zener diode ZD
_1, the diode D ₃ and the control winding 34 are connected in series, the other end of the control winding 34 is grounded. Further, the capacitor C ₂ is interposed between the cathode and the other end of the control winding 34 of the diode D _3, the resistance R ₄ of the other end is grounded between the base and the resistor R ₃ of the transistor Tr ₅ is It is connected.

The secondary circuit 16 is provided with a secondary winding 36 wound to have an additional polarity.
₄ is connected and the other end is grounded. A capacitor C ₃ and a voltage control circuit 38 are connected in parallel with the secondary winding 36, and a DC voltage is output from both ends of the voltage control circuit 38. A resistor R ₅ , a light emitting diode D ₅ constituting the photocoupler 26, and a shunt regulator 40 are connected in series to the voltage control circuit 38.
₆ and R ₇ are connected in series. The reference voltage terminal of the shunt regulator 40 is connected to the resistors R ₆ and R ₇
Connected between

In operation, if the DC input is prioritized, an electromotive force is induced in the primary winding 12, thereby generating an electromotive force in the control winding 34, the secondary winding 36, and the drive winding 24. Here, by was smoothed by induced capacitor C ₂ to the control winding 34 voltage, without the Zener diode ZD ₁ is conducting, the transistor Tr ₅ is also not conduct, there is no possibility that the PWM control circuit 32 is stopped. Thus, the secondary winding 36 is always generated electromotive force of the additive polarity, the electromotive force by being smoothed by the capacitor C ₃ is rectified by the diode D _4, DC voltage of about 6V is output. Therefore, the resistor R ₇ of the voltage control circuit 38
The, takes the voltage of 2.5V, a constant current flows through the shunt regulator 40 in accordance with this, the light emitting diode D ₅ emits light at a constant amount. As a result, the drive winding 24
Starting current when the current and AC voltage due to the induced electromotive force is input is, since to conduct all the transistors Tr _2, AC input side primary circuit 12 does not operate.

On the other hand, when the AC input is prioritized, first, the transistor Tr ₁ is turned on by the starting current, whereby an electromotive force is induced in the primary winding 18. Therefore, electromotive force is induced in the drive winding 24, a current based thereon is input to the base of the transistor Tr _1, the current flowing through the primary winding 18 increases. In this way, the collector current and the base current of the transistor Tr ₁ is increased, when can not satisfy the current amplification factor β between the collector current and the base current of the transistor Tr _1, the transistor Tr ₁ is rapidly turned off . Accordingly, counter electromotive force is induced in the drive winding 24, together with the charge is accumulated in the capacitor C _1, the counter electromotive force is induced in the secondary winding 36, the light emitting by smoothed voltage capacitor C ₃ diode D ₅ emits light. Incidentally, the capacitor C ₁ is provided, by providing a potential difference between the emitter of the collector and the phototransistor Tr ₃ of the transistor Tr _2, in order to widen the control range of the phototransistor Tr _3. Also, if the AC input is prioritized, and conducts the Zener diode ZD ₁ by induced electromotive force of the control winding 34, the transistor Tr ₅ is rendered conductive, PWM control circuit 32 is turned off. Therefore, the primary winding 28 does not conduct.

[0014] emitting diode D ₅ emits light, and conducts phototransistor Tr _3, the base input of the transistor Tr ₁ is pulled into the transistor Tr _2. The induced electromotive force of the primary winding 18 fluctuates according to the amount of pull-in,
Since the induced electromotive force of the secondary winding 36 also fluctuates, the DC output is adjusted. That is, since the DC output is greater than 6V, increases the quantity of light from the light emitting diode D _5, becomes large pull-in amount of the transistor Tr _2, 2 winding 36
And the DC output also decreases. On the other hand, when the DC output is less than 6V, the emission quantity of the light emitting diode D ₅ is reduced, the pull-in amount of the transistor Tr ₂ is reduced, the DC output is increased. In this way, the DC output is stabilized at about 6V.

[0015] Since the DC output is constant quantity of light from the light emitting diode D ₅ as long as it is 6V, the input regardless of whether the DC is AC, but the pull-in amount of the transistor Tr ₂ is constant because the starting current in case of a current and AC input based on an induced electromotive force of the drive winding 14 of the DC-input priority is only compared to the base current of the transistor Tr ₁ in the case of AC input priority, There is no problem in the operation of the circuit 10.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is an illustrative view showing a conventional technique;

FIG. 3 is a circuit diagram showing another conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Simultaneous input prevention circuit 12 ... AC input side primary circuit 14 ... DC input side primary circuit 16 ... Secondary circuit 24 ... Drive winding 26 ... Photocoupler 32 ... PWM control circuit 34 ... Control winding 38 ... Voltage control circuit

Claims (1)

(57) [Scope of request for utility model registration] A self-excited RCC circuit which operates by an input obtained by rectifying an AC power source; a separately-excited RCC circuit in which a secondary circuit is shared with a secondary circuit of the self-excited RCC circuit and operates by a DC input; A photocoupler optically couples a secondary circuit and a primary circuit of the self-excited RCC circuit, operates in response to the DC input, and absorbs a starting current of the primary circuit of the self-excited RCC circuit. The simultaneous input prevention circuit, further comprising: a control winding that generates an electromotive force by the AC input; and an off unit that turns off a primary circuit of the separately excited RCC circuit based on the electromotive force. Input prevention circuit.