JPH0230628B2 - TEREBIJONHENKOKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to television deflection circuits, and more particularly to improvements in television deflection circuits having high voltage protection circuits.

A prior art television deflection circuit of interest to this invention is shown in FIG. First, the configuration of this circuit will be explained.
One end of the horizontal oscillation circuit 4 is connected to the DC power supply 1 through a step-down resistor 2 connected in series and a step-down capacitor 3 connected in parallel, and the other end is grounded. Further, the base terminal of a horizontal drive transistor 5 used with emitter grounding is connected to the signal output terminal of the horizontal oscillation circuit 4, and the collector terminal of the transistor is connected to the horizontal drive transformer 6.
connected to the primary winding of the One side of the secondary winding of the horizontal drive transformer 6 is grounded, and the other side is connected to the base terminal of the horizontal output transistor 7. The horizontal output transistor 7 is also used with its emitter grounded, and its collector terminal is connected to the primary winding of the flyback transformer 12.
The other end of the primary winding of the flyback transformer 12 is connected to the DC power supply 1. One end of the secondary winding of the flyback transformer 12 is grounded, and the other end is connected to the anode terminal of the cathode ray tube 14 via a high voltage rectifier diode 13. The horizontal output transistor 7 and the flyback transformer 12 are connected in parallel to ground by a horizontal resonant capacitor 8, a damper diode 9, and a horizontal deflection coil 10 and an S correction capacitor 11 connected in series.
One end of the quaternary winding of the flyback transformer 12 is grounded, and the other end is connected to the high voltage protection circuit 10 through a detection voltage rectification diode 17 connected in series and a detection voltage rectification capacitor 18 connected in parallel.
1, and the high voltage protection circuit 101 is connected to the base terminal of the horizontal drive transistor 5. Here, the high voltage protection circuit 101 includes a Zener diode 26, an SCR 30, and resistors 27, 28,
29. One end of the tertiary winding of the flyback transformer 12 is grounded, and the other end is connected to a vertical oscillation/drive circuit 19 through a series-connected low-voltage rectifier diode 15 and a parallel-connected low-voltage rectifier capacitor 16. This vertical oscillation/drive circuit 19 is connected to a vertical output circuit 102, and its configuration is as shown in the figure. That is, one feedback terminal of the vertical oscillation/drive circuit 19 is connected to the vertical output point 32.
The other end of this vertical deflection coil 25 is connected to the vertical oscillation/drive circuit 1.
It is connected to the other feedback terminal of 9. and,
The collector terminal of the first vertical output transistor 21 is connected to the DC power supply 1, and the base terminal thereof is connected to the DC power supply 1 via the vertical output bias resistor 20. In addition, this vertical output transistor 21
The emitter terminal of is connected to the vertical output point 32, and the vertical output point 32 is connected to the vertical output bias diode 22.
This cathode terminal is connected to the collector terminal of the second vertical output point transistor 23. This second vertical output transistor 23 is used with its emitters grounded, and its base terminal is connected to the vertical oscillation/drive circuit 19. Furthermore, the first vertical output transistor 2
The base terminal of 1 is connected to the second vertical output transistor 2
It is connected to the collector terminal of 3.

Next, the operation of this circuit will be explained. Receiving the signal from the horizontal oscillation circuit 4, the horizontal drive transistor 5
The horizontal drive transformer 6 operates, and the horizontal output transistor 7 operates in response to this, and a voltage is generated in the flyback transformer 12. by the way,
If this voltage rises abnormally, the high voltage protection circuit 101
operates, and the detected voltage is the Zener diode 2
6, the Zener diode 26 is turned on, a voltage is applied to the gate of the SCR 30, and the SCR 30 is turned on. Here, SCR30 receives power from DC power supply 1,
Since it is applied to the base of the horizontal drive transistor 5, the horizontal drive transistor 5 remains on and therefore the horizontal output transistor turns off.
In such a case, the operation of the flyback transformer 12 operated by the horizontal output transistor is also stopped, and the generation of high voltage is stopped. However, since the low voltage generated in the tertiary coil of the flyback transformer 12 naturally stops generating, the low voltage is rectified and the energization of the vertical oscillation/drive circuit 19 that is energized thereby is stopped. It happens. Therefore, the drive output from the vertical oscillation/drive circuit 19 to the vertical output circuit 102 disappears,
The second vertical output transistor 23 is turned off, and the vertical output point 32 is charged to the voltage +B of the DC power supply 1 through the vertical output bias resistor 20 and the first vertical output transistor 21.
The coupling capacitor 24 connected to the terminal 2 is required to have a withstand voltage higher than the +B voltage.

By the way, since +B is usually 110 to 130V, the coupling capacitor 24 must have a withstand voltage of 160V and a capacitance of 100 to 220 μF. However, this has a large shape and requires a large area when the vertical output circuit is placed on a printed wiring board, and is also weak in vibration resistance, so it is necessary to fix the coupling capacitor with an adhesive. In addition, the use of such large coupling capacitors naturally increased the cost.

Therefore, an object of the present invention is to provide a compact and integrated low-cost television deflection circuit by using a small capacitor with low withstand voltage as a coupling capacitor.

In summary, the present invention provides a television deflector configured to supply the detection output of a high-voltage protection circuit to a vertical output circuit as well, and to reduce the DC potential at the vertical output point of the vertical output circuit to zero when the high-voltage protection circuit is operating. It is a circuit.

The above objects and features of the invention will become more apparent from the detailed description given below with reference to the drawings.

FIG. 2 shows a deflection circuit for a television receiver as an embodiment of the present invention. As is clear from FIG. 2, the configuration of this circuit is almost the same as the conventional television deflection circuit shown in FIG. The only difference is that the cathode terminal of the SCR 30 is connected to the second vertical output transistor 2 via a lead wire 31 through a series connection of a resistor 33 and a diode 34.
It is connected to the base terminal of No. 3. Also,
A resistor 35 and a diode 36 are connected in series between the cathode terminal of the SCR 30 and the base terminal of the horizontal drive transistor 5.
3 and diode 34 are inserted to appropriately shunt the cathode output of SCR 30.

The circuit of FIG. 2 operates as follows. When an abnormally high voltage is generated in the flyback transformer 12 and the detected voltage exceeds the Zener voltage of the Zener diode 26, a voltage is applied to the gate of the SCR 30 and the SCR 30 is turned on. In this case, the base terminal of the horizontal drive transistor 5 is biased by a voltage applied from the DC power supply 1 through the resistor 29, SCR 30, resistor 35 and diode 36, and remains on. Therefore, the operation of the horizontal output transistor 7 and, by extension, the flyback transformer 12 is stopped, and at this time, the vertical drive output of the vertical oscillation/drive circuit 19, which receives power from the tertiary winding of the flyback transformer 12, is also stopped.

By the way, in this circuit, the detection output of the high voltage protection circuit is not only from the horizontal drive transistor 5 but also from the resistor 33 connected in series from the SCR 30.
It is also supplied to the base terminal of the second vertical output transistor 23 via the diode 34 and lead wire 31. Since a voltage is applied to the collector terminal of the second vertical output transistor 23 from the DC power supply 1 through the resistor 20, the high voltage protection circuit 1
The detection output of 01 is the vertical output transistor 23
The transistor is turned on by applying it to the base terminal of the transistor. As a result, the base terminal of the first vertical output transistor 21 is grounded by the second vertical output transistor 23, so that the terminal voltage becomes approximately zero, and the first vertical output transistor 21 is turned off. Therefore, the vertical output circuit 10
A voltage is not applied to the vertical output point 32 in FIG. 2 from the DC power supply 1 through the first vertical output transistor 21. Further, the vertical output point 32 is grounded through the vertical output bias diode 22 and the second vertical output transistor 23,
Eventually, the voltage applied to the coupling capacitor 24 also becomes almost zero.

In this example, since the discrete circuit is shown, the number of parts increases by about 5.
The disadvantage of this is smaller than that of reducing the size of the coupling capacitor 24. Furthermore, when converting circuits into ICs as is generally done, these new parts are also integrated into ICs.
It can be placed internally, eliminating the need for an increase in the number of parts.

As described above, according to the present invention, even when the high-voltage protection circuit is operating, the vertical output point of the vertical output circuit is not applied with the potential of the DC power supply voltage, so that the coupling capacitor has a withstand voltage that is higher than normal. Just use the one with the highest withstand voltage that is closest to the voltage being applied (35 to 50V for the circuit in question).
Due to the miniaturization of the capacitor, measures against vibration such as adhesion are not required, and a low-cost television deflection circuit that is compact and integrated as a whole can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a television deflection circuit as an interesting prior art related to this invention.
FIG. 2 is a circuit diagram of one embodiment of the present invention. In the figure, 1 is a DC power supply, 5 is a horizontal drive transistor, 7 is a horizontal output transistor, 12
2 is a flyback transformer, 20 is a vertical output bias resistor, 21 is a first vertical output transistor, 2
2 is a vertical output bias diode, 23 is a second vertical output transistor, 24 is a coupling capacitor, 26 is a Zener diode, 30 is a
SCR, 31 indicates a lead wire.

Claims (1)

[Scope of Claims] 1. A horizontal deflection circuit, a high voltage generation circuit operated by the output of the horizontal deflection circuit, a cathode ray tube connected to the high voltage generation circuit, and a vertical deflection tube energized by receiving an energization output from the high voltage generation circuit. a vertical deflection circuit consisting of an oscillation/drive circuit and a vertical output circuit that is activated in response to the output of the vertical oscillation/drive circuit; and an output of the horizontal deflection circuit that detects an abnormal voltage rise in the high voltage generation circuit. The vertical output circuit includes a coupling capacitor and a deflection coil connected in series between the feedback terminals of the vertical oscillation/drive circuit, and receives a DC voltage from a DC power supply,
bias supply means for applying a bias voltage to a vertical output point that is a connection point between one feedback terminal of the drive circuit and the coupling capacitor; and a bias supply means coupled between the vertical output point and ground potential;
It includes an output transistor driven in response to a drive output from the vertical oscillation/drive circuit, and electrically connects the vertical output point and the ground potential in response to the detection output of the abnormal voltage rise of the high voltage protection circuit. The television deflection circuit further comprises potential setting means for setting the potential of the vertical output point to approximately zero by connecting to the vertical output point. 2. The potential setting means includes the output transistor and a detection output supply means for supplying the detection output from the high voltage protection circuit to the output transistor, and the output transistor becomes conductive in response to the detection output. , a television deflection circuit according to claim 1.