JPS6043705B2 - Correction circuit for pink tension distortion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is intended to enable appropriate horizontal deflection and pincushion distortion correction in a left and right pincushion distortion correction circuit of a television receiver.

As a correction circuit for left and right pincushion distortion with little loss, a circuit as shown in FIG. 1 has been proposed.

That is, between the input coil IA of the flyback transformer 1 and the ground, the collector-emitter of the switching transistor 2 and the resonance capacitor 3 are connected in parallel, and the horizontal deflection coil 4 and the S-shaped correction The capacitor 5 and the coil 6 are connected in series. Furthermore, a damper diode 7 is connected between the input coil IA and the ground.
8 are connected in series, and the midpoint of the connection between diodes 7 and 8,
Another S is connected between the connection midpoint of the capacitor 5 and the coil 6.
A character correction capacitor 9 is connected to the diode 8, and an anode of a thyristor 10 such as a GCS is connected to the diode 8.
The cathodes are connected in parallel. And transistor 2
A drive pulse with a horizontal period is supplied from the horizontal oscillation circuit 21 to the base of the thyristor 10, and the gate of the thyristor 10 is
A phase modulated pulse (voltage) Vg is supplied from the modulation circuit 22 .

In such a circuit, the voltage waveform and current waveform of each part are as shown by solid lines in FIG. 2, and horizontal deflection and pincushion distortion are corrected.

That is, the pulse from the oscillation circuit 21 causes the period Ti
Since the transistor 2 is turned on as shown in FIG. 2A, its collector voltage Vf is zero. However, during this period T1, the voltage charged in the capacitors 5 and 9 is discharged through the lines 31 and 32 shown in FIG. As the currents 1y and Im flow, electromagnetic energy is accumulated in the coils 4 and 6. Then, in period T2,
Since transistor 2 is turned off, coil 4 is turned off during period T1.
, 6 causes current to flow through lines 31 and 32 shown in FIG. 3B.

However, this current gradually decreases, and accordingly, the currents 1y and Im of the coils 4 and 6 also gradually decrease. Also,
Since the capacitor 3 is charged, the voltage Vf gradually increases. Furthermore, during the period T3, a current flows only through the line 32, as shown in FIG. 3C, mainly due to the energy stored in the coil 6.

Then, in period L, the energy stored in the coil 6 becomes 0, but the voltage Vf charged in the capacitor 3 is now discharged through the line 33 as shown in FIG. As the voltage Vf gradually decreases, the currents 1y and Im gradually increase in the opposite direction. Then, in period T5, the voltage Vg from the modulation circuit 22 turns on the thyristor 10 as shown in FIG. 2B, so a current flows through the line 34 as shown in FIG. From this point on, the current 1m decreases.

Furthermore, in period T6, the capacitor 3 is discharged. Then, during periods T4 and T5, the energy stored in the coils 4 and 6 causes current to flow through the lines 35 and 36, charging the capacitors 5 and 9, as shown in FIG. 3F. .

However, the currents in these lines 35 and 36 gradually become smaller. Since this operation is repeated with the operation of periods T1 to T6 as one cycle, the current 1y flowing through the deflection coil 4 becomes a sawtooth wave current with a horizontal period as shown in FIG. 2D.

In this case, if the phase at the time when the thyristor 10 turns on (at the start of period T5) is advanced, the current 1
The amplitude (peak-to-peak value) of m becomes smaller.

Also, in period T6, the capacitor 9 is connected to the line 3.
5 and the current flowing through line 36, that is, the current that is the difference between current 1y and Im (Iy-1m
), if the current 1m becomes smaller, the charging current of the capacitor 9 becomes larger. Therefore, the charging voltage of the capacitor 9 at the start of the period T1 following this period T6 becomes larger, so that the current 1y becomes smaller. The amplitude increases. Therefore, as the phase at which the thyristor 10 is turned on advances, the amplitude of the deflection current 1y increases.
By controlling the phase of the deflection current 1y, the amplitude of the deflection current 1y changes accordingly, and it is therefore possible to correct the left and right pincushion distortion. Thus, according to this circuit, pincushion distortion can be corrected simultaneously with horizontal deflection. Moreover, in that case, the current is 1 during the damper period T6.
Since y does not flow through the thyristor 10, there is an advantage that there is little loss.

However, in this circuit, in reality, due to the S-shaped correction, the current 1 m has the waveform shown by the broken line in FIG. 2E, and Im>0 in a part of the period T6.

Therefore, during this period of Im>0, a current flows from the coil 6 to the capacitor 3 through the broken line 37 shown in FIG. 3F and resonates, so that the flyback pulse voltage Vf
As shown by the broken line in FIG. 2C, the resonant pulse voltage Vr
are superimposed, causing inconvenience in horizontal scanning. This invention attempts to solve these problems.

Therefore, in the present invention, as shown by the broken line in FIG. 2B, the on-period of the thyristor 10 is set to
The coil 6 is damped by extending the period up to r.

An example of this will be explained below. In FIG. 4, a differential amplifier 40 is configured by transistors 41 and 42, and a parabolic voltage p with a vertical period is taken out from the vertical deflection circuit 25 as shown by the broken line in FIG. 6A. Vp is supplied to the base of the transistor 41, and a vertically periodic sawtooth wave voltage ■v is also taken out from the deflection circuit 25, and this voltage Vv is supplied to the base of the transistor 42.

In addition, the horizontal feedback coil 1 of the flyback transistor 1
B is connected to the base of a transistor 51 with a common emitter, the collector of this transistor 51 is connected to the base of a transistor 53 with a common emitter, and the collector of this transistor 53 is connected through a capacitor 54 to the base of a transistor 55 with a common emitter. and its base is connected to the power supply line through a resistor 56.

Then, the collector of the transistor 55 is connected to the transistor 5.
7, and its collector-emitter is connected between the base of transistor 51 and ground. In this way, the shaping circuit 50 is configured. Further, a resistor 61 and a capacitor 62 are connected in series between the collector of the transistor 51 and the ground, and a midpoint between the resistor 61 and the capacitor 62 is connected to the base of the transistor 41 .

The collector of the transistor 41 is connected to the gate of the thyristor 10 through a transistor 63 whose emitter is grounded. According to this configuration, the coil 1B of the transformer 1 receives a horizontal feedback pulse P as shown in FIG. 5A.
h is obtained, and this pulse Ph is supplied to the transistor 51, so at the rising edge of the pulse Ph (period group).

5), the transistor 51 is turned off and its collector potential VC1 becomes '4r3 as shown in FIG. As shown in Figure C, it becomes ゜゜0゛. Therefore, the base potential of the transistor 55 ■
B5 decreases at time t1 as shown in FIG. 5D, transistor 55 is turned off, and its collector potential VC5 reaches the level of ゜1゛ as shown in FIG. 5E, so that transistor 57 becomes It turns on from time t1.

Therefore, even if the pulse Ph rises after a predetermined time, the states of these transistors 51, 53, 55, and 57 continue. However, the base potential VY). Even if it drops immediately,
Since capacitor 54 is charged through resistor 56,
The potential Vb5 gradually increases from time t1.

Therefore, at time T2 determined by the time constants of capacitor 54 and resistor 56, transistor 55 is turned on, transistor 57 is turned off, transistor 51 is turned on, and transistor 53 is turned off. Therefore, the collector potential VCl becomes "1" during the period T2, as shown in FIG. 5B.

Then, if VCl="1", this causes the resistor 6 to
1, the capacitor 62 is charged through ■C1=6゛0゛2, the capacitor 62 is discharged, so that a sawtooth wave voltage h with a horizontal period is obtained in the capacitor 62 as shown in Fig. 5F. .

Since this voltage h is supplied to the base of the transistor 41, and the vertical parabolic voltage Vp is supplied from the vertical deflection circuit 25 to the base of the transistor 41,
As shown in FIG. 6A, the transistor 41 receives a superimposed voltage V of a horizontal sawtooth voltage Vh and a vertical parabolic voltage ■p.
a will be supplied. In this case, since feedback is generally applied to the deflection circuit 25, the parabolic electric box Np from now on will contain a sawtooth wave voltage component, but the vertical sawtooth wave voltage component will be included separately from the deflection circuit 25. Since the electric current V is taken out and supplied to the transistor 42, the sawtooth wave voltage component included in the parabolic voltage Vp is canceled out by the voltage Vv.

Then, the superimposed voltage Va is sliced at the level Vs in the differential amplifier 40. Therefore, as shown on the left side of FIG. 6B, at the top and bottom of the screen, the voltage Vh is lower than the slice level Vs, so the transistor 6
3 collector, as shown on the left side of Figure 6 C and D,
A voltage Vg with a slow rising phase is obtained, and in the center of the screen, as shown on the right side of FIG. 6B, the voltage Vh becomes higher with respect to the slice level S. As shown on the right side of D, the rising phase of voltage Vg becomes earlier. Therefore, at the top and bottom of the screen, the amplitude of the horizontal deflection current peak becomes small, and at the center of the screen, the amplitude of the current y becomes large, so that the pincushion distortion on the left and right sides of the screen is corrected.

In this way, horizontal deflection and left and right pincushion distortion are corrected. In this case, in particular, according to the present invention, since the time point (2) of the trailing edge of the potential VCl is delayed by the elements 53 to 57, The positive peak point of the voltage Vh at the time T2 (time T2) is also delayed, and therefore the time when the voltage g falls is delayed, and as shown by the broken line in FIG. 2B and C, the resonant pulse voltage Vr is The thyristor 10 remains on until the period.

Therefore, the positive current Im generated in the coil 6 during the period RI7r6 is also bypassed through the capacitor 9 and the thyristor 10, and does not flow to the capacitor 3 through the line 37 (FIG. 3 F), so that this resonance pulse Voltage Vr is no longer generated. Therefore, appropriate horizontal deflection can be performed. As described above, according to the present invention, horizontal deflection and pincushion distortion can be efficiently corrected, and resonance between the coil 6 and the capacitor 7 can be prevented.

In the example of FIG. 7, when the pulse Ph falls, the capacitor 73 is discharged relatively quickly through the diode 71 and the resistor 73, but when the pulse Ph falls, the capacitor 73 is discharged relatively quickly through the resistor 74. The capacitor 73 is slowly charged and the voltage ■C similar to that shown in Fig. 5B is reached.
1 is formed.

[Brief explanation of the drawing]

Figure 1 is a connection diagram for explaining this invention, Figures 2 and 3 are diagrams for explaining it, Figure 4 is a connection diagram of an example of this invention, and Figures 5 and 6 are diagrams for explaining it. An explanatory diagram, FIG. 7, is a partial connection diagram of another example of the present invention. 1 is a flyback transformer, 4 is a horizontal deflection coil, 21
25 is a horizontal oscillation circuit, and 25 is a vertical deflection circuit.

Claims (1)

[Claims] 1. A first series circuit in which a horizontal deflection coil, a first capacitor, and another coil are connected in series;
A second series circuit in which diodes are connected in series, a resonant capacitor, and a first switching element are connected in parallel, a second switching element is connected in parallel to the second diode, and the first switching element is connected in parallel to the second diode. A second capacitor is connected between a connection midpoint of the capacitor and another coil and a connection midpoint of the first and second diodes, and a horizontal periodic pulse is supplied to the first switching element. a horizontal deflection current is supplied to the horizontal deflection coil, a phase control pulse is supplied to a control terminal of the second switching element to control on/off of the second switching element,
The phase control pulse is a pulse that rises during the latter half of the horizontal retrace period, the leading edge of this pulse is phase modulated by a parabolic wave with a vertical period, and the trailing edge is a pulse that rises during the latter half of the horizontal retrace period, and the trailing edge is a pulse that rises during the latter half of the horizontal retrace period. The pulse is extended until approximately the point at which the second switching element is turned on, and the pincushion distortion is corrected by turning on and off the second switching element, and the resonance between the other coil and the resonance capacitor occurs during the conduction period of the diode. A pincushion distortion correction circuit, wherein the pincushion distortion is damped by the second switching element.