JPH0314861Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention uses a flyback transformer (hereinafter referred to as FBT) as a power supply during normal operation in television receivers, etc.
It is called. ) Relates to a start-up circuit for a horizontal oscillation circuit using output.

(Prior art) A horizontal oscillation circuit that uses the FBT output as a power source and adopts the FBT isolation method needs to obtain the power for initial startup from the preheating power supply. Conventionally, the circuit for this purpose was It was configured as shown in the figure.

This circuit outputs the output of the power transformer 1 into which commercial power is input via the preheating switch S1.
Rectifier 2 rectifies it, Zener diode ZD1 sets it to an appropriate voltage, and capacitor C1 smoothes it to obtain preheating DC voltage E ₁ , and the DC voltage E ₁ is
It is supplied as power to the horizontal oscillation circuit via the reverse current blocking diode D1.

In this circuit, if the main switch (not shown) is not turned on, even if the horizontal oscillation circuit operates, the subsequent circuits (horizontal output circuit, etc.) do not operate, so the FBT outputs no output. do not have.

However, when the main switch is turned on, an output is output from the FBT, and the DC voltage E ₂ obtained by rectifying and smoothing the voltage obtained there is input to terminal 3, and the reverse current blocking diode D 2 (this diode D2, together with the diode D1, constitutes a non-interference circuit that prevents the voltages _E1 and _E2 from interfering with each other. Continue operation.

Among the DC voltages supplied to the horizontal oscillation circuit as a power source, voltage _E1 is the voltage set by Zener diode ZD1 (for example, 9 to 10v), and voltage _E2 is the voltage set by FBT.
The latter voltage _E2 is applied to the Zener diode ZD2 via the diode _D2 and the resistor R2, and becomes the voltage set here (for example, 12V).

However, in the above startup circuit, as long as the preheat switch S1 is turned on, the voltage is
The configuration is such that E ₁ is constantly supplied to the horizontal oscillation circuit,
This has caused problems in terms of reliability and energy saving of elements such as ICs that constitute the horizontal oscillation circuit.

(Purpose of the invention) The present invention was made in view of the above points, and its purpose is to provide a horizontal oscillation start-up in which starting power is supplied to the horizontal oscillation circuit only when the main switch is turned on. The purpose is to provide circuits.

(Structure of the invention) For this purpose, the invention supplies power for startup from the power supply circuit for preheating, power for normal operation from the FBT, and supplies it to the oscillation circuit via a non-interference circuit. In the horizontal oscillation start-up circuit, a relay coil with a back electromotive force absorbing diode connected in parallel is connected to the output side of the power supply circuit, and an npn transistor that receives a remote control signal is connected at the base between the relay coil and ground. A PNP transistor is connected in series between the output side of the power supply circuit and the non-interference circuit, a switch operated by the excitation of the relay coil is connected as a main power switch, and a first transistor is connected between the emitter and base of the NPN transistor. A resistor is connected between the common connection point of the relay coil and the first transistor and the second resistor.
A second resistor was connected between the base of the transistor and the base of the transistor.

(Example) Hereinafter, an example of the present invention will be described. Second
The figure shows one embodiment, and the same parts as in FIG. 1 are given the same reference numerals. Q1
is an npn type switching transistor, its base is connected to terminal 4, which receives a power-on signal from a remote control, etc., and its collector is connected to a relay coil L and a diode D3 for absorbing the back electromotive force of the coil L. It is connected to the output side of the rectifier 2 via a parallel circuit. The relay coil L is used to turn on and off the main switch S2. Q2 is connected between the output side of rectifier 2 and resistor R1
This is a pnp type switching transistor, and a base circuit is formed by resistors R3 and R4.

Now, in this embodiment, while the power-on signal does not arrive at the terminal 4, the transistor Q1 is off and the transistor Q2 is also off. Therefore, even if the preheat switch S1 is on and a DC voltage appears from the rectifier 2, no power is supplied to the horizontal oscillation circuit.

When a power-on signal arrives at terminal 4, transistor Q1 is turned on, thereby exciting relay coil L and turning on main switch S2.
Therefore, most of the circuits within the television receiver are supplied with power. However, as it is, there will be no output from FBT.

At this time, the other transistor Q2 is also turned on at the same time as the transistor Q1 is turned on, and a DC voltage _E1 appears on its output side. Therefore, the horizontal oscillation circuit is started up by the voltage E ₁ and starts oscillating, and this oscillation causes the FBT to output an output, thereby supplying the DC voltage E ₂ to the terminal 3. Then, the power supply voltage applied to the horizontal oscillation circuit changes from E ₁ to E ₂ , and from now on this voltage
Regular oscillation continues due to E ₂ .

(Effects of the invention) As described above, according to the invention, startup power is supplied to the horizontal oscillation circuit only when the main switch is turned on, so the reliability of the horizontal oscillation circuit can be ensured. This is also preferable from the point of view of energy saving. In addition, since the relay coil for main switch switching control and the PNP transistor for start-up are commonly connected to the load side of the NPN transistor operated by remote control signals, main switch control and start-up circuit control are The circuit parts are made common and simplified, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional horizontal oscillation start-up circuit, and FIG. 2 is a circuit diagram of a horizontal oscillation circuit according to an embodiment of the present invention.

Claims (1)

[Claims for Utility Model Registration] Horizontal oscillation start in which power for start-up is supplied from the power supply circuit for preheating, and power for normal operation is supplied from the flyback transformer to the horizontal oscillation circuit via a non-interference circuit. In the up circuit, a relay coil with a back electromotive force absorbing diode connected in parallel is connected to the output side of the above power supply circuit, and an NPN transistor whose base receives a remote control signal is connected between the relay coil and the ground. A PNP transistor is connected in series between the output side and the non-interference circuit, a switch operated by the excitation of the relay coil is connected as the main power switch, and a first resistor is connected between the emitter and base of the PNP transistor. and a common connection point between the relay coil and the first transistor and the second transistor.
A horizontal oscillation start-up circuit characterized in that a second resistor is connected between the base of the transistor.