JPS6211105Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for correcting left and right pincushion distortion in a cathode ray tube, and in particular allows for easy and reliable adjustment.

A conventional left and right pincushion distortion correction circuit is configured as shown in FIG. 1, for example. In FIG. 1, reference numeral 1 indicates an input terminal, through which a vertical drive signal is supplied to the vertical output amplifier 2 from a previous-stage vertical drive circuit (not shown). A deflection current is supplied from this vertical output amplifier 2 to a vertical deflection coil 3 and also to a circuit 4 for S-shaped correction. This S-shaped correction circuit 4 consists of a series circuit of a capacitor 5 and a resistor 6. In this case, a parabolic voltage is generated across the S-shaped correction circuit 4. This parabolic voltage is passed through a capacitor 7 to an integrating circuit 8.
is supplied to This integrating circuit 8 is composed of a series circuit of a variable resistor 9 and a capacitor 10.
This integrating circuit 8 changes the phase of the parabolic voltage. The output of the integrating circuit 8 is supplied to the base of an amplification transistor 12 via a variable resistor 11. One end of the primary winding 13a of the pink coupling transformer 13 is connected to the collector of the transistor 12, and the other end is connected to the power supply terminal 14. In this case, by varying the resistance value of the variable resistor 11, the amplification factor of the amplifier made up of the transistor 12 can be varied, and the level of the parabolic voltage can be varied. Note that 15 and 16 are bias resistors, and 17 is an emitter resistor.

On the other hand, the secondary winding 1 of the pink union transformer 13
One end of 3b is grounded, and the other end is connected to one end of horizontal deflection coil 19 via capacitor 18. The other end of this horizontal deflection coil 19 is connected to a power supply terminal 20 and to the collector of a horizontal drive transistor 21 . Note that a damper diode 22 and a resonance capacitor 23 are connected in parallel to the collector-emitter path of this horizontal drive transistor 21.
Needless to say, it is connected. Further, 24 is a horizontal drive signal supply terminal.

As already mentioned, in such a conventional circuit, the phase of the parabolic voltage can be varied by varying the resistance value of the variable resistor 9, and the phase of the parabolic voltage can be varied by varying the resistance value of the variable resistor 9.
By varying the resistance value of 1, the level of the parabolic voltage can be varied. Left and right pincushion distortion can be corrected by setting the phase and level of the parabolic voltage to appropriate values. This requires no explanation.

However, in such a conventional example, when the resistance value of the variable resistor 9 is varied, not only the phase of the parabolic voltage but also the level of the parabolic voltage changes. Conversely, if the resistance values of the other variable resistors 11 are varied, not only the level of the parabolic voltage but also the phase of the parabolic voltage will change slightly. Therefore, correct left and right pincushion distortion correction cannot be performed unless the phases and levels of the parabolic voltages are adjusted in a complementary manner, and the work is extremely complicated. At the same time, it was also difficult to perform accurate correction.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a left-right pincushion distortion correction circuit that can easily and reliably correct left-right pincushion distortion.

An embodiment of the left and right pincushion distortion correction circuit of the present invention will be described below with reference to FIG. Note that in FIG. 2, parts corresponding to those in FIG. 1 are designated by corresponding symbols, and explanations thereof will be omitted.

In FIG. 2, another integrating circuit 31 is used in place of the integrating circuit 8 of the example shown in FIG. This integrating circuit 31 consists of a variable resistor 32 and a capacitor 10 having two fixed terminals and one movable terminal. The variable terminal of the variable resistor 32 is grounded via the capacitor 10. The output of the integrating circuit 31 is also supplied to the base of an emitter follower type transistor 34 via a capacitor 33. Note that 35 is an emitter resistor, and 36 is a bias resistor. Further, the front stage of the capacitor 33 is grounded via a resistor 37. The emitter output of the transistor 34 is supplied to the base of a subsequent transistor 40 via a series circuit of a variable resistor 38 and a capacitor 39.

In such a configuration, the phase of the parabolic voltage can be varied by operating the movable terminal of the variable resistor 32. Here, the resistance values of the variable resistor 32 and the resistance values of the resistor 37 are assumed to be ΔR ₁ , ΔR ₂ and R as shown in the figure. When the variable resistor 32 is operated to make ΔR ₁ small (ΔR ₂ naturally becomes large), the phase of the parabolic voltage advances. Of course, if ΔR ₁ is made small and the phase of the parabolic voltage is advanced, the divided voltage of the parabolic voltage by ΔR ₁ and the capacitor increases. However, at this time, ΔR ₂ becomes large, so the voltage divided by ΔR ₂ and resistor 37 decreases, and as a result, the level of the parabolic voltage supplied to transistor 34 hardly changes. Conversely, if ΔR ₁ is increased, the phase of the parabolic voltage will be delayed. And in this case too, the level hardly changes. This is easy to understand. As described above, even if the phase of the parabolic voltage is varied, the level of the parabolic voltage does not change.

The level of the parabolic voltage can be changed by changing the resistance value of the variable resistor 38. In this case, since impedance conversion is performed by the emitter follower transistor 34, the variable resistor 3
Most of the variation in the resistance value of 8 is due to the integration circuit 31 in the previous stage.
does not affect. That is, even if the level of the parabolic voltage is varied, the phase of the parabolic voltage hardly changes. As described above, in this example, since the phase and level of the parabolic voltage can be adjusted independently, the workability is good and the adjustment can be performed extremely easily and reliably.

As described above, according to this left and right pincushion distortion correction circuit, the waveform of the parabolic voltage is adjusted using the variable resistor 32 consisting of two fixed terminals and one movable terminal, so even if the phase is varied, the parabolic voltage does not change. Changes in level can be almost ignored. On the other hand, an emitter follower transistor 34 is inserted between this variable resistor 32 and a variable resistor 38 for varying the level of the parabolic voltage, so that changes in the resistance value of the variable resistor 38 hardly affect the variable resistor 32 in the previous stage. Therefore, the level adjustment of the parabolic voltage can be performed independently of the phase adjustment.
For this reason, the present invention can easily and reliably correct left and right pincushion distortion.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various changes can be made without departing from the spirit of the invention.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional left and right pincushion distortion correction circuit, and FIG. 2 is a circuit diagram showing an embodiment of the left and right pincushion distortion correction circuit of the present invention. 10 is an integrating capacitor, 13 is a pincushion transformer, 31 is an integrating circuit, 32 is a variable resistor for phase adjustment, 34 is an emitter follower type transistor, and 38 is a variable resistor for level adjustment.

Claims (1)

[Scope of utility model registration request] A parabolic waveform current with a vertical period is supplied to the base of the emitter follower transistor through the path between the fixed terminals of a first variable resistor consisting of two fixed terminals and one movable terminal. A right and left pincushion distortion correction circuit, wherein an integrating capacitor is connected to the movable terminal of the resistor, and the output of the transistor is supplied to a pincushion distortion correction transformer via a second variable resistor.