JPS5879435A - Power source supply system for electronic equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (11) Technical Field of the Invention The present invention relates to an improvement in a power supply system for electronic equipment equipped with an alarm circuit for monitoring a drop in supply voltage.

(2) Background of the technology Various specified voltages are used as power supplies for various electronic devices that include various electronic components such as transistors and ■C, or mechanical components such as relays and motors in addition to these. A power transformer, a rectifier circuit, a smoothing circuit with individual secondary wires to be generated, a rectifier circuit, a smoothing circuit, and control of the application order, in other words, the application time between various specified voltages in order to perform the normal function, as well as the control of the application time, and the control of the application time during operation. It consists of an alarm circuit that monitors a drop in the specified voltage due to overcurrent, etc.

For example, 5V as a supply voltage to semiconductor components such as transistors and ICs, or! In a power supply system where 2V is prepared and 24V is prepared as the supply voltage to mechanical parts such as relays and motors, first 5V is prepared when the power is turned on.
It is designed so that v1 or 12V is supplied to a predetermined circuit, and after a short delay, u■ is supplied. This is because the control circuit must be prepared in advance of the operation of the mechanical component. At the same time, when the power is cut off, the 24V supply voltage to the mechanical parts is cut off and then 5■ or 4;! The 12 V supply voltage is disconnected with a slight delay.

In FIG. 1, time t is plotted on the horizontal axis to show the time course of the various supply voltages mentioned above, where Tn indicates the time when the power is turned on and Tf indicates the time when the power is turned off.

Delay time t1 from Tn at power-on of u■, and 5■
, or the delay time t2 from the 12V power-off time Tf are both formed as one of the functions of the respective power supply circuits.

The alarm circuits for each supply voltage are configured as a common circuit to avoid the uneconomical cost of installing them individually:
For this purpose, it is necessary to stop the function of this common alarm circuit during time periods t1 and t2 (not shown in FIG. 1). This is because the normal operating time of this electronic device is one hour during which various specified voltages are applied to the device.

(3) Prior art and problems Conventionally, for this purpose, a special secondary dark line was provided in the power transformer, and an independent circuit consisting of a complex combination of TTL (transistor, transistor logic) etc. was used, which reduced production costs. In addition to being expensive, the large number of parts also contributed to a decrease in the reliability of the circuit.

(4) Purpose of the Invention It is an object of the present invention to provide a novel power supply system of this type that eliminates these drawbacks.

(5) Structure of the Invention This object of the present invention is that the DC voltage directly derived from one of the main DC power supply lines of the power transformer has a time constant of an alarm detection circuit together with at least one main DC voltage supply. This is achieved by configuring a configuration that controls a switching circuit with

In other words, instead of providing an independent alarm inhibiting circuit by providing a special secondary dark line in the power transformer as in the prior art, a configuration is provided in which the alarm detection circuit has the above-mentioned inhibiting function.

The alarm detection circuit is provided with a switching element, such as a thyristor, which closes the alarm circuit when one of the main supply DC voltages falls below a specified voltage by more than a specified value. By adding a time constant circuit to this and providing a function to prevent the time line alarm circuit from closing slightly from the time the power is turned on, malfunctions of the alarm circuit that may occur transiently at time t1 shown in Figure 1 can be prevented. To prevent.

(6) Embodiment of the Invention FIG. 2 is a circuit diagram of a main part showing an embodiment of the present invention, in which commercial power is supplied to the primary dark line 2 of the power transformer 1, and the secondary dark lines 3.3', 3'' pass through 4.4° and 4" circuit networks including rectifier circuits, smoothing circuits, delay circuits, etc., respectively, and
, 12V, 24V main DC voltage. In this case, the delay function included in the circuit network 4.4° corresponds to time t2 in FIG. 1, and the delay function included in the circuit network 4'' corresponds to time t1 in the same figure.

On the other hand, the secondary (DC voltage drawn directly from winding 3'' and rectified) passes through resistor R1 to control power supply C for sequence circuits, etc.
It is further supplied to the collector of the transistor Q via a resistor R2, and the supply DC voltage of 24V, 5.5V is applied to its base via a Zener diode DID2, etc., as shown.

Further, the collector voltage of the transistor Q is applied to the thyrisk-Th inserted in the alarm circuit AL via a time constant circuit consisting of a resistor R3 and a capacitor C1, a Zener diode D3, and a smoothing circuit. The portion surrounded by chain lines constitutes an alarm detection circuit and an alarm prohibition circuit.

First, the functions in the normal state (period T in FIG. 1) will be explained.

In this state, both 24v and 5v are at normal voltages, the base potential of transistor Q is also normal and on, and the collector (point B) potential is lower (lower), and Zener diode D3 is off, so thyristor Th is also off. The alarm circuit AL is cut off.

If the supply DC voltage of 24V or 5■ is caused by some reason (
For example, if the base potential of f1 transistor Q falls below the specified value due to overload (for example, overload), the base potential of f1 transistor Q falls and turns off, and the collector potential rises and turns Zener diode D3 on, supplying the gate voltage of Thyrisk-Th. turns it on and closes the alarm circuit AL.

Next, a function for keeping the alarm circuit AL in an OFF state during a period t1 from power-on shown in FIG. 1 will be explained.

The collector potential of the transistor Q rises at the same time as the power is turned on, and in order to prevent the thyristor Th of the alarm circuit AL from turning on because the 24V supply supervision pressure is not yet applied, a time constant circuit consisting of a resistor R3 and a capacitor C1 is connected to the collector.・Connected between chisels. As shown in the lower part of Figure 1, the collector voltage of the transistor Q increases for a period of t1 until 24V is applied to the base electrode, and once it is applied, the transistor Q turns on and drops to zero potential, reaching a steady state. . As described above, the alarm circuit AL is then switched to the closed state due to a decrease in the supplied DC voltage.

When the power is cut off, the supply voltage of 5 or 12 V is
Even if two periods remain, the alarm circuit AL cannot be closed because the collector potential of the transistor Q is zero potential.

(7) As described in the detailed description of the invention, in the present invention, two independent
By adding a switching circuit with a time constant to the naturally necessary alarm detection function, it is possible to provide a prohibition function without the need to provide a secondary conductor, simplifying the configuration itself and reducing the number of parts. This has many effects, such as avoiding a decline in reliability.

Originally, the present invention is not limited to the illustrated embodiments;
Appropriate modifications may be made within the scope of the claims.

[Brief explanation of drawings]

Figure 1 shows a characteristic diagram to explain the alarm prohibition function.
FIG. 2 is a main circuit diagram showing one embodiment of the power supply system according to the present invention. In the figure, 1 is a power transformer, Q is a transistor, and Di
, D2. D3 is a Zener diode, h is a thyristor, R1, R2, R3 are resistors, C is a capacitor, A
L indicates an alarm circuit.

Claims (1)

[Claims] characterized in that the direct current voltage derived directly from one of the main direct current supply windings of the power transformer controls a switching circuit with a time limit 1 provided in the alarm detection circuit together with at least one main direct current supply voltage. A power supply system for electronic equipment equipped with an alarm circuit to monitor a drop in supply voltage.