JPS6130354Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a television receiver that uses both AC and DC power supplies, and particularly relates to a starting circuit for its horizontal oscillation circuit section.

2. Description of the Related Art Conventionally, it has been known to connect a horizontal oscillation circuit section in an AC/DC dual purpose television receiver configured as shown in FIG. 1 to an AC power source and a DC power source. That is, when using AC power supplies A and C, the DC voltage obtained through the transformer T ₁ , rectifier diode D ₁ and smoothing capacitor C ₁ is applied to the control transistor Q ₁ and the error amplification transistor.
It is supplied to each load circuit via the DC stabilizing circuit ST consisting of _Q2 , and the horizontal oscillation circuit H-
The +B voltage is supplied to the OSC via a resistor _R6 , which is reduced to a predetermined voltage.

In addition, when using the DC power supply D/C, the switching regulator SR is connected via the pulse width control and drive circuit PWC/D, the switching transistor Q ₃ , the output transformer T ₂ , the rectifier diode D ₈ and the smoothing capacitor C ₅ . The DC voltage obtained from the horizontal oscillation circuit H-OSC is supplied to the horizontal oscillation circuit H-OSC via the resistor _R6 . In this case, during steady state, the output of the horizontal oscillation circuit H-OSC is used as a switching signal to control the pulse width and drive circuit.
In order to supply and control the PWC/ _D , _the horizontal oscillation _{circuit H-}
OSC section and pulse width control and drive circuit
It is as if each PWC/D is activated.

By the way, in the power supply circuit of the conventional television receiver as described above, the horizontal oscillation circuit H-
+B voltage supplied to OSC is AC power supply A/C
When the +B voltage is used, the +B voltage rises slowly, that is, with a slight delay, because it is supplied through an integrating circuit consisting of a resistor _R6 and a decoupling capacitor _C6 . As a result, the horizontal oscillation circuit H-OSC takes some time for the oscillation frequency and oscillation output level to reach the normal values, and as a result, abnormal noise is generated from the horizontal output transformer FBT, albeit for a short time. There was such an inconvenience.

Therefore, in order to eliminate this kind of thing, it is necessary to resist
It is possible to make the rise of the +B voltage faster by reducing the value of _R6 , but then the horizontal oscillator circuit H-OSC must be operated with a high +B voltage even in steady state, so the DC power supply D.
There was a problem in that it became difficult to start up when using C. It is also possible to speed up the rise of the +B voltage by connecting an electrolytic capacitor in parallel with the low resistance R ₆ , but when starting up with a DC power supply D/C, a reverse polarity voltage is applied to the electrolytic capacitor. When the electrolytic capacitor becomes conductive, the horizontal oscillation circuit H-
This is undesirable because it becomes equivalent to directly connecting a large-capacity capacitor _C5 to the +B voltage line of the OSC, which causes a problem of interfering with startup.

This idea was made in view of the above points, and it is possible to easily and reliably speed up the rise of the +B voltage supplied to the horizontal oscillation circuit when using an AC power supply, and also to speed up the start-up when using a DC power supply. It is an object of the present invention to provide an extremely good power supply circuit for a television receiver that can prevent interference.

An embodiment of this invention will be described in detail below with reference to the drawings.

In other words, in Figure 2, AC is a commercial alternating current power supply, and is connected to a transformer through switch _S1 .
Connected to the primary side of _T1 . This transformer transformer T ₁
One end of the secondary side is grounded, and the other end is connected to the collector of the switching transistor _Q1 via a rectifier diode _D1 of the illustrated polarity, and is also grounded via a smoothing capacitor _C1 . The switching transistor Q ₁ has a resistor R ₁ connected between its collector and base, and its base is grounded via a capacitor C ₂ and also connected to the collector of an error amplification transistor Q ₂ , and its emitter is connected to a diode D ₂ . It is connected to the output terminal OUT via the resistor _R2 , and to the emitter of the error amplification transistor _Q2 via the resistor R2. Also, the base of this error amplification transistor _Q2 is connected to the output terminal.
It is connected to the midpoint of resistors R ₃ and R ₄ connected in series between OUT and ground, and a Zener diode D ₃ for reference voltage is connected between the emitter and ground, and the collector has a pulse width as described below. It is connected to a predetermined part of the control and drive circuit PWC/D.
Here, the switching transistor Q ₁ and the error amplification transistor Q ₂ constitute a series control type DC stabilizing circuit ST, and its output terminal OUT generates horizontal oscillation through a resistor R ₆ and a diode D ₉ in series. It is connected to the +B power supply terminal of the circuit H-OSC and also to other load circuits (not shown).

On the other hand, D/C is a DC power source such as a battery, and is connected to the switching regulator SR via switch _S2 .
Connected to one end of the primary side of the output transformer _T2 that constitutes the The other end of the primary side of this output transformer _T2 has a pulse width control and drive circuit PWC/
It is connected to the output terminal of D and to the collector of a switching transistor _Q3 whose emitter is grounded. In addition, the output transformer _T2 has one end of the secondary side grounded, and the other end of the secondary side connected to the output terminal OUT via a rectifier diode _D8 with the polarity shown, and is also grounded via a smoothing capacitor _C5 . . and said pulse width control and drive circuit
PWC/D has its input terminal connected to the horizontal oscillation circuit H-
It is connected to the output terminal of the OSC, one power supply terminal is connected to the output terminal OUT, and the other power supply terminal is connected to the output transformer T through a diode _D7 and a capacitor _C4 of the illustrated polarity in series. Connected to one end of the primary side of ₂ . Here, the connection midpoint between diode _D7 and capacitor _C4 is grounded via diode _D6 of the illustrated polarity. Further, one end of the primary side of the output transformer _T2 is grounded via a resistor _R5 and connected to the +B power supply terminal of the horizontal oscillation circuit H-OSC via a capacitor _C3 and a diode _D5 . Here, the capacitor
The midpoint of connection between _C3 and diode _D5 is grounded via a diode _D4 of the illustrated polarity, and the +B power supply terminal of the horizontal oscillation circuit H-OSC is grounded via a decoupling capacitor _C6 .

In the above configuration, the diode D ₉ is connected to the pressure reducing resistor R ₆ connected between the +B power supply terminal and the output terminal OUT of the horizontal oscillation circuit H-OSC.
are connected in series according to the polarity shown, and the resistor
A feature of this invention is that capacitor _C7 is connected across _R6 in parallel.

That is, in the above configuration, the operation itself when AC power supplies A/C or DC power supplies D/C is used is approximately the same as that of the conventional power supply described above, but especially when AC power supplies A/C are used, the capacitor C ₇ is connected in parallel to the resistor _R6 , so that the rise of the +B voltage supplied to the horizontal oscillation circuit H-OSC becomes faster due to the differential action of the capacitor _C7 . At this time, the diode
Since D ₉ is in the forward bias state, it is in the on state and also in the steady state after startup, so the +B voltage is supplied to the horizontal oscillation circuit H-OSC via the resistor R ₆ and the diode D ₉ . I can continue.

As a result, the horizontal oscillator circuit H-OSC immediately enters the normal operating state after the switch _S1 is turned on, so that undesirable phenomena such as abnormal sounds generated from the horizontal output transformer FBT etc. as in the conventional case are avoided. can be prevented from occurring.

Furthermore, when starting up when using a DC power source D/C, the output voltage from the switching regulator section is zero at the moment immediately after switch _S2 is turned on, and voltage is applied to the anode side of diode _D9 . Since the starting voltage due to the charging current of the capacitor _C3 supplied from the capacitor _C3 and the diode _D5 is applied to the cathode side of the diode _D9 , the diode _D9 is in a reverse bias state and becomes an off state. Thereby, said capacitor C ₃
The charging current no longer flows into the smoothing capacitor _C5 via the capacitor _C7 , and can only be used to start the horizontal oscillation circuit H-OSC, thus preventing any interference with the start-up. can do. In this case, when startup is finished, the charging current of capacitor _C3 disappears, so diode _D9 is forward biased by the output voltage from the switching regulator, so it becomes on state, and resistor _R6 and diode D ₉ , the +B voltage from the switching regulator is supplied to the horizontal oscillation circuit H-OSC, and a steady state is established.

Therefore, as detailed above, according to this invention, horizontal oscillation can be easily and reliably achieved by simply connecting a capacitor in parallel with the resistor interposed in the +B power supply line of the horizontal oscillation circuit and connecting a diode in series. It is an object of the present invention to provide an extremely good power supply circuit for a television receiver, which can speed up the rise of the +B voltage supplied to the circuit when using an AC power supply and prevent interference with starting when using a DC power supply. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing the main parts of the power supply circuit of a conventional television receiver, and FIG. 2 is a wiring diagram of the main parts showing one embodiment of the power supply circuit of the television receiver according to this invention. A/C...AC power supply, ST...stabilization circuit,
D・C...DC power supply, SR...Switching regulator, H-OSC...Horizontal oscillation circuit, _C3 ,
C ₆ , C ₇ ... Capacitor, R ₆ ... Resistor, D ₅ , D ₉ ...
...Diode, OUT...Output terminal.

Claims (1)

[Claims for Utility Model Registration] It has a horizontal oscillation circuit, and a first DC voltage obtained through a stabilizing circuit that rectifies and stabilizes an AC voltage or from a DC power source is applied to the power supply end of the horizontal oscillation circuit. A second DC voltage obtained through a switching regulator that switches the voltage of
At startup when using a DC voltage of In a power supply circuit of a television receiver, which is supplied as a switching signal to an oscillator, the second DC voltage is applied between the power supply terminal of the horizontal oscillation circuit and the pressure reducing resistor at the time of startup. A diode is connected in series with a polarity that is reverse biased by a DC voltage generated by a charging current and is forward biased during steady state and when the first DC voltage is used, and is connected across the pressure reducing resistor. A power supply circuit for a television receiver characterized by connecting capacitors in parallel.