JPS6025179Y2 - Deflection distortion correction circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a deflection distortion correction circuit for reducing color shift caused by differences in horizontal deflection distortion of each image pickup tube in a color television camera using a plurality of image pickup tubes.

Conventionally, in color television cameras that use multiple image pickup tubes, color shifts caused by differences in horizontal deflection distortion of each image pickup tube have been corrected by controlling the position, magnitude, and linearity of the horizontal deflection. .

For example, in a color television camera that has an image pickup tube that outputs red, green, and blue, this method is used to adjust the horizontal deflection distortion of the image pickup tube that outputs green to a minimum, and then This was done by adjusting the position, magnitude, and linearity of the horizontal deflection so that the horizontal deflection distortion of the image pickup tube used to obtain the output was minimized.

In this case, trapezoidal deflection distortion and pincushion deflection distortion caused by variations in the deflection coil and image pickup tube could not be corrected.

Therefore, in order to reduce trapezoidal distortion and pincushion distortion, there is a method of selecting a combination of a deflection coil and an image pickup tube, or adjusting the positional relationship of the horizontal deflection coil, vertical deflection coil, and focus magnetic field generating coil that make up the deflection coil. was taken.

Of these two methods, in the case of the former method, it is necessary to manufacture many deflection coils in order to select a combination that fits within the allowable color shift, and the selection process is very time-consuming. Ta.

On the other hand, in the latter method, when selecting a combination, in order to determine the position of the deflection coil, it is necessary to disassemble the coil into pieces that can be repositioned many times, which also requires a lot of effort.

In addition, even after these steps are taken, it is often not possible to bring the color shift within the allowable range.

Furthermore, even after these combinations are determined, when the imaging tube reaches the end of its lifespan and is replaced, the relationship between the characteristics of the deflection coil and the imaging tube changes, often resulting in color shift.

In such a case, it is impossible to select the above-mentioned combination of the deflection coil and the image pickup tube in the field where the color television camera is used, so the occurrence of color shift has to be accepted.

This idea was made in order to eliminate the above-mentioned drawbacks of the conventional technology. The trapezoidal distortion and pincushion distortion of the horizontal deflection component are electrically corrected in the horizontal deflection circuit, and the horizontal deflection caused by the combination of characteristics of the image pickup tube and the deflection coil. It is an object of the present invention to provide a deflection distortion correction circuit capable of correcting pincushion distortion and trapezoidal distortion of deflection components and reducing color shift occurring between image pickup tubes.

Embodiments of the deflection distortion correction circuit of this invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of one embodiment.

TR in FIG. 1 is a transistor.

The base of this transistor TR is connected to the input terminal 1.

A horizontal deflection drive pulse P1 is input to the input terminal 1.

This horizontal deflection drive pulse P1 drives the transistor TR, and during the horizontal retrace period, the transistor TR is driven.
is in a cut-off state.

The emitter of the transistor TR is grounded, and the collector is connected to the output terminal of the buffer amplifier A through an inductance element.

A damper diode D1 is connected between the collector and emitter of the transistor TR, and is also connected to one end of the horizontal deflection coil LH via a coupling capacitor C□.

The other end of the horizontal deflection coil LH is grounded, and a capacitor C2 is connected in parallel thereto.

On the other hand, 2 to 6 are terminals, and terminal 2 is connected to the input end of the buffer amplifier A via a resistor R□.

A variable resistor VR□ is connected between terminals 3 and 4.

The movable terminal of variable resistor VR□ is coupling capacitor C
buffer amplifier A through the series circuit of 3 and resistor R2.
is connected to the input end of the

Further, a variable resistor VR2 is also connected between terminals 5 and 6.

The movable terminal of this variable resistor VR2 is connected to the input end of the buffer amplifier A through a series circuit of a coupling capacitor C1 and a resistor R3.

A DC voltage for controlling the magnitude of horizontal deflection is applied to the terminal 2, and the terminal 3
, 4 have different polarities and are applied with sawtooth waves of equal level.

Furthermore, parabolic waveforms having different polarities and equal levels are applied to the terminals 5 and 6.

The twisting capacitor C3 is for cutting the DC component of the sawtooth wave.

Next, the operation of the deflection distortion correction circuit of this invention constructed as described above will be explained.

Transistor TR is driven by the horizontal deflection drive pulse applied to input terminal 1, is turned off during the horizontal retrace period, and is resonated by the inductance Lh of horizontal deflection coil L)I and capacitor C2 (including stray capacitance) and is fried. Generates back pulse.

This is a common horizontal deflection circuit.

In FIG. 1, the magnitude of horizontal deflection is determined by the DC voltage applied across the inductance element.

The above operation is that of a conventionally known horizontal deflection circuit, but this invention has the following features.

That is, by superimposing a sawtooth wave or a bipolar waveform formed using a vertical deflection drive pulse on the DC voltage E, the voltage that determines the magnitude of horizontal deflection is changed, and the trapezoidal distortion of the horizontal deflection component or the pincushion This allows distortion to be corrected.

This operation will be explained in more detail below.

A DC voltage for controlling the magnitude of horizontal deflection is applied to the terminal 2, and is applied to the inductance element through the resistor R□ and the buffer amplifier A.

Furthermore, if sawtooth waves with different polarities and approximately the same level are applied to terminals 3 and 4, the sawtooth waves can be superimposed on the DC voltage via resistor R2 by adjusting variable resistor VR□. .

For example, when the movable terminal of the variable resistor VR□ is on the terminal 3 side, a polar sawtooth wave whose level increases as time passes is added to the DC voltage that determines the magnitude of horizontal deflection.

Therefore, the output (DC voltage E) of the buffer amplifier A (assuming it is non-inverting) is as shown in FIG.

At this time, if you look at the horizontal deflection on the cathode ray tube of the video monitor, you will notice that the voltage applied to the horizontal deflection circuit of the image pickup tube, which determines the magnitude of the horizontal deflection, is The level is lower than that below.

For this reason, the sweep width of the beam that sweeps over the target of the image pickup tube decreases and narrows at the top of the screen, and on the video monitor, the width in the horizontal direction is wide at the top of the image and narrow at the bottom.

In other words, if a rectangular figure was imaged, the image on the video monitor would look like the broken line in Figure 3 (
As the sweep width of the horizontal deflection of the image pickup tube becomes narrower, the horizontal width of the screen on the video monitor becomes wider.

) On the other hand, if the movable terminal of the variable resistor VR device is placed on the terminal 4 side, the voltage that determines the magnitude of horizontal deflection will be as shown in Figure 4, and the reproduction on the video monitor when a rectangular drawing is taken The image will look like the broken line in FIG.

That is, by changing the variable resistor VR1, the trapezoidal distortion of horizontal deflection can be changed.

Therefore, in a color television camera that uses a plurality of image pickup tubes, it is possible to reduce the trapezoidal distortion component of the difference between the horizontal deflection distortion of the reference image pickup tube and the horizontal deflection distortion of other image pickup tubes.

Similarly, if the polarity and level of the parabolic waveform applied to terminals 5 and 6 are changed using variable resistor VR2, variable resistor VR
When the movable terminal 2 is on the terminal 5 side, the voltage waveform that determines the magnitude of horizontal deflection is as shown in FIG. 6, and when the movable terminal is on the terminal 6 side, it is as shown in FIG.

In the waveform shown in FIG. 6, the horizontal deflection of the image pickup tube sweeps wide at the center of the screen, and the horizontal width of the image on the video monitor screen becomes narrow.

That is, if a rectangular figure is imaged, it can be viewed on a video monitor as shown by the broken line in FIG.

In the waveform shown in FIG. 8, the relationship is reversed and the rectangular shape can be seen on the video monitor as indicated by the broken line in FIG.

That is, by varying the variable resistor VR2, it is possible to reduce the difference in pincushion distortion between the image pickup tubes, as in the case of trapezoidal distortion.

As described above, according to the deflection distortion correction circuit of this invention, a DC voltage is applied via an inductance element to the collector of a transistor that performs a switching operation using a horizontal deflection drive pulse, and the inductance of the horizontal deflection coil and the capacitor are In the horizontal deflection circuit of a color television camera that generates flyback pulses in a resonant circuit to perform horizontal deflection operation, pulses generated from vertical deflection drive pulses are used to generate sawtooth and parabolic waveforms with different polarities and equal levels. Since the DC voltage applied to one of the inductance elements is superimposed by adjusting the variable resistor, it is possible to reduce the difference between trapezoidal distortion and pincushion distortion in the horizontal deflection of each image pickup tube.

Along with this, it is possible to reduce color shift by simply adjusting the variable resistor, without adjusting the position of each deflection coil or selecting a combination of deflection coil and image pickup tube.

Therefore, the adjustment time can be shortened compared to the conventional case, and even when the image pickup tube is replaced, there is no color shift as in the conventional case, readjustment can be done by moving the variable resistor, and maintenance This also leads to improved sexual performance.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the deflection distortion correction circuit of this invention, and FIGS. 2 to 9 are diagrams for explaining the operation of the same deflection distortion correction circuit, respectively. 1...Input terminal, 2-6...Terminal, T
R...Transistor, C□, C3, C,...
...Coupling capacitor, C2 ... Capacitor, A ... Buffer amplifier, L ...
...Inductance element, LH...Horizontal deflection coil, R1 to R3...Resistance〇

Claims (1)

[Scope of utility model registration request] a transistor that is driven by a horizontal deflection drive pulse and is cut off during a horizontal retrace period to perform a switching operation; an inductance element that has one end connected to the collector of the transistor and applies a DC voltage to the collector from the other end; A horizontal deflection coil that forms a resonant circuit with this capacitor to generate a flyback pulse to perform horizontal deflection operation, and a sawtooth wave of different polarity created from the vertical deflection drive pulse. a first variable resistor to which a voltage is applied to both ends to superimpose the sawtooth wave voltage on the DC voltage; and a parabolic waveform voltage of different polarity generated from the vertical deflection drive pulse to be applied to both ends to superimpose the sawtooth wave voltage on the DC voltage. A deflection distortion correction circuit comprising a second variable resistor that superimposes a waveform voltage on the DC voltage.