KR970004358B1 - Inrush current protection and demagnetization circuit - Google Patents

Abstract

The present invention provides a sudden current control and degaussing circuit which cuts off application of abnormal current when applying AC power to an electronic equipment's power terminal, and removes a magnetic field created in the electronic equipment. This circuit may be used in devices highly consuming power, such as television sets, etc., which lowers the power consumption, protecting the main electronic devices. This circuit includes a transistor (Q6) connected to a control signal input terminal (C) to actuate a triac (TH1) finally; a delay condenser (CS) charging DC current; the triac (TH1) turning on diodes (D9, D10, D11, D12) and a degaussing coil (Ld) on receipt of a trigger current; a transistor (Q5) to which DC voltage is applied through the transistor Q4; a condenser (C8) charging DC voltage by bridge rectification; and a serial circuit part of thermistor (PTC) and coil (Ld).

Description

Inrush Current Limit and Device Circuit

1 is a detailed circuit diagram of a conventional inrush current limiting and device circuit.

2 is a detailed circuit diagram of the inrush current limiting and device circuit of the present invention.

* Description of the symbols for the main parts of the drawings *

TH1: Triac

Q ₁ , Q ₂ , Q ₃ : Transistors for forward detection

Q ₄ , Q ₅ , Q ₆ : Transistors C ₁ , C ₂ , C ₃ , C ₄ : Net detection capacitor

C ₅ : delay capacitor hd: element coil

D ₇ ~ D ₁₂ : Rectifier diode C ₈ : Rectifier smoothing capacitor

[Technical Field]

The present invention relates to an inrush current limiting and element circuit for blocking abnormal inrush current input when supplying AC power to a power terminal of an electronic device, and for erasing a magnetic field generated in the electronic device by a geomagnetism. In particular, the present invention relates to inrush current limiting and element circuits for protecting expensive electronic devices used in high power consumption devices such as television receivers.

[Background of invention]

Generally, in an electronic device having a built-in condenser input rectifier circuit for converting a commercial AC power into a DC power source, when the first AC power is input to the electronic device, an inrush current charged to the rectifier smoothing capacitor in the rectifier circuit is usually several hundred amps. In order to damage the contact point of the switch, blow the fuse, or destroy the rectifier diode, and to generate noise in other devices, the inrush current limiting circuit is used to cut off the inrush current. .

Conventionally, as shown in FIG. 1, a resistor (R ₁ ) of a few Ω is installed between the AC power input line (L ₁ ) and the rectifier circuit to limit the inrush current, but the power at the resistor (R ₁ ) The loss is very large, especially the higher power consumption device, the power loss is increased. Therefore, the power consumption of the device is increased according to the trend of high-end and large-sized household electronics today, effectively reducing the inrush current In addition, a circuit that can significantly reduce power consumption in an inrush current limiting circuit is required.

On the other hand, in a color television receiver using a CRT having a shadow mask, a device coil is used every time the water receiver is turned on by using an element coil around the CRT to prevent color purity from being degraded by a geomagnetic field.

In the related art, as shown in FIG. 1, a static characteristic thermistor (PTC) is connected in series to the element coil Ld, and the relay switch SW ₁ is intermittently interlocked with the ON / OFF operation of the TV receiver. In an electronic device such as a TV receiver which needs to simultaneously perform the inrush current limiting function and the device function described above, a current limiting circuit and a separate device circuit should be provided.

[Purpose of invention]

In view of the foregoing, the present invention effectively prevents inrush current during power-on, reduces power consumption, and inrush current limiting and device circuits capable of operating the function of the device coil without a separate relay switch. The purpose is to provide.

In order to achieve the above object, the inrush current limiting and element circuit according to the present invention uses an alternating current bidirectional silicon switching element (TRIAC) instead of the relay switch (SW ₁ ), operating the element coil, as well as the power supply The power consumption at the resistor R _{1 due} to the inrush current is greatly reduced.

[Summary of invention]

Inrush current limiting and element circuit according to the present invention is connected to one side (L ₂ ) of the commercial AC power input terminals (L ₁ , L ₂ ), and is connected to the control signal input terminal (C) to finally operate the triac (TH1) and a transistor (Q ₆₎ to that, the transistor (Q _6), a diode (D ₄₎ and a resistor (R ₁₃₎ delay capacitor (C ₅₎ for charging the direct current voltage through the, main switching by oN / OFF of the main power The high frequency voltage held in the secondary winding of the transformer (T ₁ ) is rectified through the diode (D ₆ ) and the smoothing capacitor (C ₇ ) to generate a trigger current through the resistor (R ₁₅ ) and the transistor (Q ₅ ) as a DC power source. Triac (TH1) to turn on rectifier diodes (D ₉ , D ₁₀ , D ₁₁ , D ₁₂ ) and element coil (Ld), and capacitor (C ₅ ) divided by resistors (R ₁₁ , R ₁₂ ). low direct current voltage across the transistor is supplied through the transistor (Q ₄₎ (Q ₅₎ and a rush current limiting is connected to the commercial AC power source input terminals (L ₁₎ (R ₁₇₎ and a rectifying diode through a triac (TH1), each capacitor (C ₈ to charge the direct current voltage by the bridge rectifier action of the _{(D 7, D 8, D} 9, D 10, D 11, D 12) ) And the series circuit part of thermistor (PTC) and element coil (Ld) operated by trigger of triac (TH1) by ON / OFF of main power supply to prevent excessive inrush current inflow when power is turned on. to and is at the same time protecting the host device to erase the magnetic field present in the host device, the sheet input side L ₂ Capacitor (C ₃ ) charging DC voltage through diode (D ₄ ) and resistor (R ₇ ) by half cycle, and capacitor (C) charging DC voltage through resistor (R ₁₃ ) and diode (D ₅ ). ₄ ) The discharge time constant of the capacitor C ₃ and the resistor R ₃ is smaller than the discharge time constant of the capacitor C ₄ and the resistor R ₄ , so that the cut-off state is maintained during normal operation. When the AC input generates more than one cycle of pure steps, it is turned on through the diode (D ₂ ) and passes through the resistors (R ₈ , R ₉ ), transistor (Q ₃ ), and resistor (R) to delay capacitor (C _5). A transistor (Q ₂ ) for discharging the DC voltage charged in the circuit) to block the gate trigger current of the triac TH1; L ₂ input side By a half cycle, a capacitor (C ₁ ) for charging the galvanic voltage through the diode (D ₃ ) and the resistor (R ₄ ), and a capacitor for charging a DC voltage through the diode (D ₃ ) and the resistor (R ₅ ) ( C ₂ ) and the discharge time constants of the capacitor C ₁ and the resistor R ₁ are smaller than the discharge time constants of the capacitor C ₂ and the resistor R ₂ to maintain the cut-off state during normal operation. When the AC input generates more than one cycle, a transistor is turned on through the diode D ₁ to turn off the transistor Q ₂ through the resistor R ₆ to block the gate trigger current of the triac TH2. And a forward detecting circuit section having Q ₁ ).

[Description of Specific Embodiment of the Invention]

The inrush current limit and the device circuit according to the present invention will be described in detail with reference to FIG. 2 as follows.

First, when a commercial AC voltage is input between the commercial AC power input terminals L ₁ and L ₂ , the L ₂ side When it is a half cycle, the DC voltage is charged to the capacitor C ₅ through the transistor Q ₅ , the diode D ₄ and the resistor R ₁₃ . The DC voltage across the capacitor C ₅ is divided by the resistors R ₁₂ and R ₁₁ , and the divided voltage across the resistor R ₁₁ is the threshold between the base and emitter of the transistor Q ₄ . When the voltage value is reached, the transistor Q ₄ flows the amplified collector current to flow the base current of the transistor Q ₅ into a conductive state.

The conduction of the transistor Q ₅ causes the secondary winding of the juice switching transformer T ₁ to be used in the high frequency switching type voltage stabilization device normally installed after the rectified voltage output between the output terminals A and B. The high-frequency voltage is a low voltage DC power supply rectified by the diode D ₆ and the smoothing capacitor C _{7. The} triac TH1 is provided through the emitter collector of the series resistor R ₁₅ and the transistor Q ₅ . Is supplied as a trigger current to the gate side of the gate.

As described above, since the triac TH1 is triggered after a delay (charging time constant) is delayed by the time of charging the capacitor C ₅ at the first power-on, the rectifier passes through the inrush current limiting resistor R ₁₇ having a relatively large value. Bridge rectification by diodes D ₇ , D ₈ , D ₁₀ , D ₁₁ causes the smoothing capacitor C ₈ to be in a state of completion of charging, at which time excessive inrush even if triac TH1 flows a turn-on current. No current is generated, and as a result of the turning on of the triac TH1, the current rectified through the resistors R ₁₇ , diodes D ₇ and D ₈ so far has passed through the triac TH1 Rectification diodes (D ₉ , D ₁₀ , D ₁₁ , D ₁₂ ) enable normal rectification.

Next, referring to the intermittent operation of the element coil Ld by the ON / OFF of the TV receiver, as described above, since the DC power supply for the trigger of the triac TH1 is supplied from the voltage stabilized switching transformer T ₁ , Without this power supply voltage, the triac TH1 is not triggered, and the transformer T ₁ of the switched stabilization power supply is controlled by ON / OFF signals such as a remote control of a TV receiver. The intermittent operation of Ld) becomes possible, and the element function in the TV receiver which is an electronic device is achieved. As described above, during the inrush current limiting and the normal operation of the device function, when a short-circuit phenomenon occurs in the commercial AC input, the charge charged in the delay capacitor C ₅ is instantaneously discharged. Therefore, the operation of the transistors Q ₄ and Q ₅ is interrupted to cut off the DC power supply for the gate trigger of the triac TH1.

On the other hand, every one supplied to the input terminal (L ₂ ) side By a half cycle, it is rectified to diode D ₄ , and a charge voltage is also generated through capacitor R ₃ through resistor R ₇ , which is charged via resistor R ₁₃ and diode D ₅ . The capacitor Q ₂ is set to be slightly higher than the voltage charged in (C ₄ ), and in the normal operation, the transistor Q ₂ remains in the cut-off state, but when the commercial AC input generates one cycle or two or more forward stages, the capacitor As the discharge time constants of (C ₃ ) and resistor (R ₃ ) are set slightly larger than the half cycle of the commercial AC voltage, the charging voltage across the capacitor (C ₃ ) is discharged before the capacitor (C ₄ ) side, The base current of transistor Q ₂ flows through diode D ₂ , which is amplified to operate transistor Q ₃ by resistor R ₉ and base bleeder resistor R ₈ . direct current charged in the capacitor (C ₅₎ via a resistor (R ₁₀₎ a voltage is quickly It is discharged.

In addition, every piece supplied to the input terminal L ₂ side According to the half-cycle, diode (D ₃₎ is rectified by a resistance (R ₄₎ (R ₅₎ a capacitor (C _1), the charging voltage to cause a charging voltage respectively to the (C ₂₎ is a capacitor (C ₃₎ through the to be generated to the voltage of the resistance (R ₂₎ and capacitor (C _2), the discharge time constant of the resistance (R ₁₎ and a capacitor (C ₁₎ by - (C ₄₎ voltage, as opposed to be filled in () The discharge time constant is set to be much smaller, and the voltage at both ends of the capacitor C ₁ is set slightly larger than the voltage at both ends of the capacitor C ₂ , and the transistor Q ₁ is cut off during normal operation. When about one cycle or more of the commercial AC power supply is smooth, the discharge time constant of the resistor R ₁ and the capacitor C ₁ is set slightly larger than the half cycle of the commercial AC power supply. is the voltage across the discharge rapidly _1), via a diode (D ₁₎ flowing a base current of the transistor (Q ₁₎ By it is, the amplified collector current is dropped flowing a base current of the transistor (Q ₂₎ via a resistor (R _6), quickly discharging the voltage charged in the capacitor (C ₅₎ as described above, the triac (TH1 Cut off the gate trigger current.

Here, the transistor Q ₆ is intended to finally start the operation of the triac TH1 in the circuit part of the present invention, so that excessive inrush current does not occur even when the circuit of the present invention is used in combination with another circuit. a diode (D ₄₎ the voltage applied to the transistor (Q ₆₎ is interrupted by a circuit different from that of the present invention by the conduction of the input a determination signal via a terminal (C) after completion of start-up transistor (Q ₆₎ The circuit is working.

As described above, the inrush current limiting and device circuit according to the present invention is the power input terminal (L ₁ , L ₂ ) to the device coil (L ₈ ) and the static thermistor (PTC) serial circuit at the moment triac (TH1) is fired By connecting a commercial AC power supply from the power supply), the loss voltage (current) generated by the inrush current limiting resistor (R ₁₇ ) set to a relatively large value is short-circuited by the triac TH1. The power consumption is reduced while performing the device function and the inrush current limiting function.

In addition, in the present invention, when the triac TH1 is triggered by a direct current, the commercial AC power supplied between the input terminals L ₁ and L ₂ generates pure steps for one cycle or several cycles due to external causes. In this case, the voltage charged in the output smoothing capacitor C ₈ is discharged to the load side and rapidly decreases. At this time, when the normal AC voltage is input again, the triac TH1 and the diode D ₉ , D ₁₀ , D ₁₁ , D ₁₂ ) It is dangerous because it flows through the lamps, so that transistors (Q ₁ , Q ₂ , Q ₃ ), etc., are installed to immediately detect the net power of the AC power supply to prevent the triac (TH1) from being kept triggered. do.

As described above, the inrush current limiting and element circuits of the present invention are used in TV receivers to effectively prevent the inflow of the inrush current generated when the power supply is turned on, thereby protecting the electronic devices and consuming the inrush current limiting function. It is a useful invention that can reduce power as much as possible and also effectively perform device functions.

Claims (2)

Is connected to a commercial AC power source input terminal side (L ₂₎ of the (L _1, L _2), it is connected to the control signal input (C) the triac (TH1) and the transistor (Q ₆₎ to be the final operation, the diode (D ₄ ) and a high frequency voltage held in the secondary winding of the juice switching transformer (T ₁ ) by the delay capacitor (C ₅ ) for charging the DC voltage through the resistor (R ₁₃ ) and the main power supply ON / OFF. ₆ ) and rectified through smoothing capacitor (C ₇ ) and receiving the trigger current through resistor (R ₁₅ ) and transistor (Q ₅ ) as DC power and rectifying diode (D ₉ , D ₁₀ , D ₁₁ , D ₁₂ ) and Triac TH1 for turning on the element coil Ld, and a transistor Q supplied with a direct current voltage across the capacitor C ₅ divided by the resistors R ₁₁ and R ₁₂ through the transistor Q | ₄ . ₅ ) and rectifying diodes (D ₇ , D ₈ , D ₉ , D ₁ ), respectively, through inrush current limiting resistors (R ₁₇ ) and triac (TH1) connected to the commercial AC power input (L ₁ ). Capacitor (C ₈ ) charging DC voltage by bridge rectification by ₀ , D ₁₁ , D ₁₂ ) and thermistor (PTC) and element operated by trigger of triac (TH1) by ON / OFF of main power An inrush current limiting and element circuit, comprising a series circuit portion of a coil Ld, to prevent excessive inrush current generated when the power is turned on, thereby protecting a claimed value and erasing a magnetic field existing in a main device. The method of claim 1, wherein the sheet input side of L ₂ Capacitor (C ₃ ) charging DC voltage through diode (D ₄ ) and resistor (R ₇ ) by half cycle, and capacitor (C) charging DC voltage through resistor (R ₁₃ ) and diode (D ₅ ). ₄ ), the discharge time constant of the capacitor C ₃ and the resistor R ₃ is smaller than the discharge time constant of the capacitor C | ₄ and the resistor R ₄ , so that the cut-off state is maintained during normal operation. When the commercial AC input generates one or more cycles of forward stages, it is turned on through the diode D ₂ , and is delayed through the resistors R ₈ , R ₉ , the transistor Q ₃ , and the resistor R. A transistor Q ₂ for discharging the DC voltage charged in the C ₅ ) to block the gate trigger current of the triac TH1; L ₂ input side The capacitor C ₁ , which charges the DC voltage through the diode D ₃ and the resistor R ₄ by a half cycle, and the capacitor C, which charges the DC voltage through the diode D ₃ and the resistor R ₅ ( C ₂₎ and a capacitor (C | ₁₎ and the resistor (capacitors the number of the discharge time constant of the R ₁₎ (C ₂₎ and keep the cut-off state at the time of small hameuroseo normal operation than the discharge time constant of the resistance (R _2), and The transistor which turns on through the diode D ₁ when the commercial AC input generates more than one cycle, turns off the transistor Q ₂ through the resistor R ₆ to block the gate trigger current of the triac TH2. An inrush current limiting and element circuit further comprising a forward stage detection circuit section having (Q ₁ ).