JPH06231664A - Power supply device - Google Patents

Abstract

PURPOSE:To make the current capacity of an relay small, and thereby lower the cost of a device. CONSTITUTION:The emitter, the collecter and the base of a transistor Tr1 are connected to a power supply circuit 2, one end of a resistor R1 and the input terminal C of a control panel (via a resistor R2) respectively. The transistor Tr1 and the resistor R1 are connected to a relay contact 2C in parallel. A delay circuit 11 which comprises a resistor R3 and a capacitor C1 connected in parallel, is connected to an output terminal A. A resistor R4 and a diode D are connected to the delay circuit 11 in series. The collector, the emitter and the base of a transistor Tr2 are connected to the junction of the base of a transistor Tr3, the delay circuit 11 and the resistor R4 via the output terminal A and a resistor R5 respectively. The collector, the emitter and the base of the transistor Tr3 are connected to a coil 2L, an output terminal B and the output terminal B (via a delay circuit 12 which comprises a resistor 6 and a capacitor C2 connected in parallel) respectively. A resistor R7 is connected to a place between the base and the emitter of the transistor Tr1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying power to electric equipment, and more particularly to a mechanism for turning on / off power supply.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing the configuration of a conventional power supply device. In the figure, reference numeral 1 is a power supply circuit, which generates a predetermined voltage between the output terminals A and B and supplies electric power to the electrical equipment connected to the output terminals A and B.

Reference numeral 2 is a relay, and a relay contact 2C is inserted between the power supply circuit 1 and the output terminal A. The coil 2L has one end connected to the connection point between the power supply circuit 1 and the relay contact 2C, and the other end connected to the collector of the transistor 3. The transistor 3 has an emitter terminal connected to the output terminal B and a base connected to the control signal input terminal C, respectively.

Thus, in the power supply device having the above-described structure, the coil 2L is energized by turning on the transistor 3 by a control signal (indicating ON / OFF of power feeding) given from the outside. 2C is turned on and power is turned on. When the transistor 3 is turned off by the control signal, the coil 2L is de-energized, the relay contact 2C is turned off, and the power supply is turned off.

By the way, the electric equipment which supplies power by the above-mentioned power supply device generally has a capacitor for circuit protection such as noise removal or surge protection. Therefore, when the relay contact 2C is turned on to start power supply, a large current instantaneously flows through the relay contact 2C to charge the capacitor of the electric device. Then, when the capacitor of the electric device is sufficiently charged, the current flowing through the relay contact 2C decreases and stabilizes.

Therefore, the relay 2 has a large capacity capable of withstanding a large current when the relay contact 2C is turned on. For this reason, the relay becomes very expensive, and the device cost is increased.

[0007]

As described above, in the conventional power supply device, at the start of power feeding, a large current instantaneously flows in the relay for turning on / off the power feeding. Although it is relatively low, it is necessary to use a relay having a current capacity capable of withstanding the above-mentioned large current, which causes a problem that the device cost increases.

The present invention has been made in consideration of such circumstances, and an object thereof is to turn on the power supply.
It is an object of the present invention to provide a power supply device that can reduce the device cost because the relay for turning off can have a small current capacity.

[0009]

The present invention includes a second switch means such as a transistor which is provided in parallel with a first switch means such as a relay contact and which is turned on / off in response to a control signal. A resistor provided in series with the second switch means and in parallel with the first switch means to limit the current flowing through the second switch means;
Potential detecting means for detecting that the potential of the output terminal has reached a predetermined value is provided, and the first potential is detected in response to the detection of the potential of the output terminal reaching the predetermined value. The switch means is turned on.

[0010]

By taking such means, the second switch means provided in parallel with the first switch means is turned on by the control signal at the start of power feeding. At this time, the current flowing through the second switch means is limited by the resistor provided in series with the second switch means and in parallel with the first switch means. Then, the first switch means is turned on when the potential detecting means detects that the potential of the output terminal reaches a predetermined value. Therefore, the first switch means, after the potential of the output terminal rises,
That is, it is turned on after the current decreases.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing the configuration of the power supply device according to this embodiment. The same parts as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, Tr1 is a pnp type transistor, the emitter of which is a power supply circuit 1 (for example, a transformer in the power supply circuit 1), the collector of which is connected to one end of a resistor R1 and the base of which is a control signal via a resistor R2. Each is connected to the input terminal C. The transistor Tr1 and the resistor R1 are connected in parallel with the relay contact 2C.

To the output terminal A, there is connected a delay circuit 11 formed by connecting a resistor R3 and a capacitor C1 in parallel. Further, a resistor R4 and a diode D are connected in series with the delay circuit 11. The diode D has an anode connected to the resistor R4 and a cathode connected to the control signal input terminal C, respectively.

Tr2 is a pnp type transistor,
The emitter is connected to the output terminal A, the collector is connected to the base of the transistor Tr3 via the resistor R5, and the base is connected to the connection point between the delay circuit 11 and the resistor R4.

The transistor Tr3 is of npn type, and has a collector connected to the coil 2L and an emitter connected to the output terminal B, respectively. In addition to the resistor R5, the base of the transistor Tr3 is connected to the output terminal B via a delay circuit 12 formed by connecting a resistor R6 and a capacitor C2 in parallel. R7 is a resistor that connects between the base and emitter of the transistor Tr1.

The power supply device configured as described above operates as follows. That is, when the control signal is set to the Low level to start power supply, current flows through the resistors R7 and R2, and the transistor Tr1 is turned on.
When the transistor Tr1 is turned on, the power supply circuit 1 and the output terminal A are connected, and power supply is started. At this time, the capacitor built in the electric device connected to the output terminal A is not charged and the output terminal A has a low potential, but the current flowing through the transistor Tr1 is limited by the resistor R1.

In this state, as the capacitor built in the electric device connected to the output terminal A is charged,
The potential of the output terminal A rises. The potential of the output terminal A is a predetermined value (the voltage drop of the diode D and the resistors R3, R4
(Determined by the resistance value of) and transistor Tr2
Turns on. However, the timing at which the transistor Tr2 turns on is slightly delayed by the action of the delay circuit 11. Then, the transistor Tr2 is turned on and the resistor R
When a current flows through the transistor 5, the transistor Tr3 is turned on. However, the timing at which the transistor Tr3 is turned on is slightly delayed by the action of the delay circuit 12 than the timing at which the transistor Tr2 is turned on. here,
The circuit composed of the transistor Tr2, the resistors R3, R4 and R5, the capacitor C1 and the diode D is provided when the potential of the output terminal A exceeds a predetermined value.
3 is turned on and operates as a potential detecting means.

When the transistor Tr3 is turned on, the coil 2L is energized, the relay contact 2C is turned on, and the power supply circuit 1 and the output terminal A are connected without a resistor. At this time, the capacitor built in the electric device connected to the output terminal A is sufficiently charged, the potential of the output terminal A is equal to or higher than a predetermined value, and the current flowing through the relay contact 2C is low and stable. ing. Here, the transistor 3, the resistor R6, and the capacitor C2 are the circuits including the transistor Tr2, the resistors R3, R4, and R5, the capacitor C1, and the diode D as described above, and the electrons at the output terminal A have a predetermined value or more. The relay contact 2C is turned on in response to the detection of the fact that it works as an on control means.

As described above, according to this embodiment, the relay contact 2C is turned on after the potential of the output terminal A has sufficiently risen, that is, after the current has dropped, so an inexpensive relay with a small current capacity can be used. Can be used.

At the start of power feeding, the transistor T
Although the power supply circuit 1 and the output terminal A are connected via r1, the current flowing through the transistor Tr1 is low because the current is limited by the resistor R1 at this time, and the transistor Tr1 also has a current capacity. It can be a small one.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the transistor is used as the second switch means, but other switching elements such as a relay may be used. The specific circuit configurations of the potential detecting means and the ON control means are not limited to those described above. In addition, various modifications can be made without departing from the scope of the present invention.

[0022]

According to the present invention, the second switch means such as a transistor, which is provided in parallel with the first switch means such as a relay contact and is turned on / off in response to a control signal, and the second switch means. A resistor that is provided in series with the switch means and in parallel with the first switch means and limits the current flowing through the second switch means, and detects that the potential of the output terminal has reached a predetermined value. An electric potential detecting means is provided, and the first switch means is turned on in response to the detection of the electric potential of the output terminal reaching a predetermined value by the detecting means. The power supply device is low, and the relay for turning on / off the power supply can have a small current capacity, and the device cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating a conventional technique.

[Explanation of symbols]

1 ... Power supply circuit, 2C ... Relay contact, 2L ... Coil, Tr
1, Tr2, Tr3 ... Transistor, R1, R2, R
3, R4, R5, R6, R7 ... Resistors, C1, C2 ... Capacitors, D ... Diodes, A, B ... Output terminals, 11,
12 ... Delay circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Tsuchida Kyoto Prefecture Kyoto City Kyoto City Oike Dori Karasuma Higashiiri 1st Line 4 Uehara Building, 3rd Floor, Uehara Bldg., 191, Nakaboricho Nichicon Corporation (72) Inventor Yuji Shiraishi Kyoto Prefecture Nichicon Co., Ltd., 3rd floor, 4 Uehara Bldg., 191, Nakaboricho, Oike Dori, Karasuma Higashiiri, Nakagyo-ku, Kyoto

Claims (1)

[Claims] 1. A predetermined potential generated in a power supply circuit is supplied to an electric device via an output terminal, and a first switch means inserted between the output terminal and the power supply circuit is externally provided. In a power supply device capable of turning on / off the power supply by turning on / off based on the control signal, a second switch provided in parallel with the first switch means and turning on / off according to the control signal. Means, a resistor provided in series with the second switch means and in parallel with the first switch means, for limiting a current flowing through the second switch means, and a potential of the output terminal having a predetermined value. And a turn-on control means for turning on the first switch means when the detection means detects that the potential of the output terminal reaches a predetermined value. Shi Power supply, characterized in that.