JPS6322755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power supply circuit using a silicon-controlled rectifying element used in television receivers and the like.

Conventional configuration and problems thereof Conventionally, this type of power supply circuit has been configured as shown in FIG. A controlled DC input voltage B 1 is supplied from the AC power input terminal 1 to the DC power input terminal 8 via a rectifying and smoothing circuit 7 consisting of four diodes 2, 3, 4, 5 and a capacitor _6. [Unregulated DC input voltage] This DC input voltage _B1 is applied to the primary winding 10 of the choke trunk 9 and the horizontal output transformer 11.
The voltage is applied to the anode of the silicon-controlled rectifier 13 via the next winding 12, and the silicon-controlled rectifier 1
A DC output voltage B ₂ derived from the cathode of No. 3 is applied to the horizontal output circuit 14 .

Here, the horizontal output circuit 14 is the horizontal output transformer 1
1, it is composed of a horizontal output transistor 15, a damper diode 16, a resonant capacitor 17, a diode 18 for absorbing abnormal pulses, a resistor 19, a capacitor 20, a horizontal deflection coil 21, and an S-shaped correction capacitor 22. Also, 26
is a starting pulse supply circuit for the silicon-controlled rectifying element 13, which is constructed by connecting the anode of a diode 41 to the anode of a constant voltage diode 40;
The cathode of the constant voltage diode 40 is connected to the DC power input terminal 8 , and the cathode of the diode 41 is connected to the gate electrode 27 of the silicon-controlled rectifying element 13 . Gate electrode 27 is connected to the cathode of silicon-controlled rectifier 13 via resistor 28 . Further, the cathode of the silicon-controlled rectifier 13 , that is, the power output terminal 29 is grounded via a capacitor 30 and connected to the DC power input terminal 8 via a resistor 31 . One end of the secondary winding 32 of the chiyoke trunk 9 is connected to the diode 3.
3, and the other end is connected to a power output terminal 29. The DC output voltage B ₂ derived from the power supply output terminal 29 is stepped down and stabilized by the resistor 34 , the voltage regulator diode 35 , and the capacitor 36 , and is supplied from the power supply terminal 37 to the error detection phase control circuit 38 .

In the constant voltage power supply circuit configured as described above, the power switch 39 is closed and the rectification smoothing circuit 7 is closed.
When input AC voltage is being supplied to the DC power supply input terminal 8, a rectified and smoothed controlled DC input voltage _B1 is derived, and this controlled DC input voltage _B1 is applied to the primary winding 10 of the pulse transformer 9. , the tertiary winding 12 of the horizontal output transformer 11, and the silicon-controlled rectifier 13, and the power output terminal 29
The voltage stabilized DC output voltage B ₂ is derived as
This DC output voltage B ₂ is supplied to the horizontal output circuit 14 and is also supplied to the error detection phase control circuit 38 after being stepped down via the resistor 34 .

When the power switch 39 is turned on, the starting pulse supply circuit 26 is activated and a starting pulse is supplied to the gate electrode 27 of the silicon-controlled rectifying element 13. This triggers the silicon-controlled rectifying element 13 to turn on, and the capacitor 30 is charged from the power input terminal 8 via the winding 10 of the choke transformer 9 and the tertiary winding 12 of the horizontal output transformer 11. When capacitor 30 is charged to a certain voltage, horizontal output circuit 14 begins horizontal deflection operation, error detection phase control circuit 38 is also ready for operation, and horizontal output circuit 14 begins to operate completely.

In the conventional circuit described above, the starting pulse supply circuit 26 is provided between the rectifying and smoothing circuit 7 and the gate electrode 27 of the silicon-controlled rectifying element 13, and the power supply switch 39
When input, the controlled DC input voltage _B1 is derived from the DC power input terminal 8, and the silicon controlled rectifier element 1
The DC output voltage derived to the cathode of 3 is B ₂ ,
If the Zener voltage of the voltage regulator diode 40 is E _z , then if B ₁ −B ₂ > E _z , the voltage regulator diode 40
Then, the diode 41 becomes conductive, the starting pulse supply circuit 26 is activated, the silicon-controlled rectifying element 13 is turned on, and the DC output voltage B ₂ rises to the rated value, starting the horizontal output circuit 14 and the like.

However, this type of conventional circuit is configured to operate based on the Zener voltage _Ez of the voltage regulator diode 40, so when the power supply voltage becomes higher than the rated value, _B1 - _Ez > _B2 ... When it comes to the relationship, the error detection phase control circuit 3
Regardless of the operation of 8, the silicon controlled rectifier 13
turns on. Therefore the zener voltage
It is necessary to choose a high value for E _z . On the other hand, when the power supply voltage becomes lower than the rated value, the starting voltage for oscillation start must satisfy the following relationship: B ₁ − B ₂ > E _z ..., and the Zener voltage E _z must be set to a higher value. If this is selected, a problem will occur where oscillation will not start when the power supply voltage drops below the rated value. As described above, the conventional circuit has the drawback that the usable range of the power supply voltage is narrow due to the restriction due to the Zener voltage _Ez of the voltage regulator diode 40.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to provide a device that can be used over a wide range of power supply voltages.

Structure of the Invention The power supply circuit of the present invention is configured to stabilize the controlled DC input voltage derived to the DC power input terminal using a silicon-controlled rectifier, and also serves as a starting pulse supply circuit for the silicon-controlled rectifier. , the controlled DC input voltage is directly stepped down by a dividing resistor, and the midpoint of the dividing resistor is connected to the other end of a silicon bidirectional switching element, one end of which is grounded, via a current blocking resistor, and the emitter of the transistor is divided. The base of the PNP transistor is connected to the midpoint of the resistor and connected to the other end of the silicon bidirectional switching element, and a diode is connected in the forward direction from the collector of the transistor to the gate electrode of the silicon controlled rectifier. It is characterized by supplying pulses.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. Components similar to those in FIG. 1 are given the same reference numerals and their explanations will be omitted.

Starting pulse supply circuit 26 of the power supply circuit of this embodiment
is structured as follows.

In FIG. 2, the controlled DC input voltage _B1 derived to the DC power supply input terminal 8 at the output end of the rectifying and smoothing circuit 7 is divided and stepped down by dividing resistors 42 and 43.
The midpoint between the dividing resistors 42 and 43 is connected via a current blocking resistor 44 to the other end of a silicon bidirectional switching element (hereinafter referred to as SBS) 45 whose one end is grounded. Further, the emitter of a PNP transistor 46 is connected to the midpoint of the dividing resistors 42 and 43, and the base of the PNP transistor 46 is connected to the intersection of the current blocking resistor 44 and the SBS 45.
A diode 47 is connected in the forward direction from the collector of the PNP transistor 46, and the cathode of the diode 47 is connected to the gate electrode 2 of the silicon-controlled rectifier 13.
7 to constitute a starting pulse supply circuit 26.

With this configuration, when the power switch 39 is turned on, the DC input voltage B ₁ is derived to the DC power input terminal 8 via the rectifier and smoothing circuit 7, and the voltage B ₃ is divided and stepped down by the dividing resistors 42 and 43.
When becomes higher than the switching voltage Vs of SBS 45, SBS 45 is turned on through the current blocking resistor 44, and the base current of PNP transistor 46 flows, so PNP transistor 46 is turned on, and silicon controlled rectification is performed through diode 47. A current flows through the gate electrode 27 of the element 13,
The silicon-controlled rectifying element 13 is turned on, and the DC output voltage _B2 rises to the rated value, starting the horizontal output circuit 14 and the like. In addition, as shown in the characteristics in Figure 3, SBS45 once turns on, the on-voltage
This element has the characteristic of rapidly decreasing to V _T and continuing to maintain the on-voltage V _T . The reason why an element with such characteristics is necessary is that the switching voltage _Vs of the SBS45 needs to be sufficiently high compared to the gate voltage V _G standard of the silicon-controlled rectifier 13, but once the silicon-controlled rectifier 13 is turned on, the silicon-controlled rectifying element 13 is controlled by the gate pulse from the error detection phase control circuit 38, so that the influence from the starting pulse supply circuit 26 is eliminated. The gate voltage of the silicon controlled rectifier 13 is at least 3 volts, and the SBS
The switching voltage V _s of the 45 is approximately 8 volts, and the on-voltage V _T is 1.4 volts. I _H is the holding current.

Therefore, after the silicon-controlled rectifier 13 is turned on, the output of the starting pulse supply circuit 26 is maintained at a value sufficiently lower than the gate voltage V _G of the silicon-controlled rectifier 13, so that it will never affect the silicon-controlled rectifier 13 again. will not be given.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

Since the starting pulse supply circuit in the power supply circuit of the present invention operates based on the characteristics of a silicon bidirectional switching element, the usage range of the power supply voltage is narrow and is subject to power supply voltage regulations, which was a drawback of the conventional Zener voltage. It is possible to always perform a good starting pulse supply operation over a wide range without any trouble, and to start the horizontal output circuit etc. reliably and stably.

[Brief explanation of the drawing]

FIG. 1 is a conventional power supply circuit diagram, FIG. 2 is a circuit diagram of an embodiment of the power supply circuit of the present invention, and FIG. 3 is a static characteristic diagram of a silicon bidirectional switching element. 8...DC power supply input terminal, 13...Silicon controlled rectifier, 26...Starting pulse supply circuit, 27
...Gate electrode, 42, 43...Division resistor, 44
... Current blocking resistor, 45 ... Silicon bidirectional switching element, 46 ... PNP transistor,
47...Diode.

Claims (1)

[Claims] 1 The controlled DC input voltage applied to the DC power input terminal is stabilized and output using a silicon-controlled rectifier, and the controlled DC input is used as a starting pulse supply circuit for the silicon-controlled rectifier. The voltage is directly stepped down by a dividing resistor, the midpoint of the dividing resistor is connected to the other end of a silicon bidirectional switching element whose one end is grounded via a current blocking resistor, and the emitter of the transistor is connected to the midpoint of the dividing resistor. The base of the transistor is connected to the other end of the silicon bidirectional switching element, and a diode is connected in the forward direction from the collector of the transistor to apply a starting pulse to the gate electrode of the silicon controlled rectifier. A power supply circuit designed to supply power.