JPH0120839B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a peripheral vertical skew correction device for a color television camera, etc., which allows registration at the peripheral portions of an image to be easily and accurately corrected independently.

Color television cameras have conventionally used multiple image pickup tubes with different spectral sensitivity characteristics, and synthesized the video signals from these tubes to obtain a color video signal. is often used.

Therefore, in an imaging device such as a color television camera that obtains a final video signal by combining video signals from multiple image pickup tubes, the final video signal is obtained from each of the multiple image pickup tubes. It is necessary to ensure that the respective images based on the video signals are accurately superimposed.

This type of superimposition of images is called registration, and requires correction of various forms of geometric distortion due to various causes. Of these, distortion where the entire image plane has a parallelogram shape Conventionally, the so-called skew (SKEW) correction method has been mainly adopted as a correction method.

However, in this conventional skew correction method, distortion is corrected by uniformly tilting the horizontal scanning line over the entire image plane, so for example, in a color television camera, it is difficult to correct the distortion of images of three RGB channels. If the images of these RGB channels are all distorted into a parallelogram shape, it is possible to perform effective correction, but if the linearity of the image plane is poor and the distortion is accompanied by a ladder shape. When correcting the center of the image plane, there will be more deviations at the periphery; on the other hand, if you correct the peripheries, there will be more deviations at the center. Although it is possible to achieve relatively accurate registration in the periphery of the image, which is susceptible to variations in the characteristics of the image pickup tubes and deflection coils used, It is difficult to correct these independently depending on the case, and there is a drawback that a large registration error tends to remain in this area.

An object of the present invention is to eliminate the drawbacks of the prior art described above, to enable skew correction in the peripheral area independently of the overall skew correction including the central part of the image plane, and to correct the skew over the entire image plane including the peripheral area. To provide a peripheral vertical skew correction device capable of sufficiently performing registration correction.

To achieve this purpose, the present invention clips and extracts the part from the maximum value of the sawtooth wave signal for vertical deflection to a predetermined voltage value, and the part from the minimum value to a predetermined voltage value, and extracts these parts. The signal obtained by multiplying the horizontal polarization sawtooth signal by the horizontal polarization sawtooth signal is superimposed on the vertical polarization sawtooth signal as a skew correction signal, and skew correction can be performed at the lower and upper peripheries independently of the center of the image. It is characterized by the fact that

Hereinafter, an embodiment of the peripheral vertical skew correction device according to the present invention will be described with reference to the drawings.

Figure 1 shows an embodiment of the present invention in which the present invention is applied to a color television camera consisting of three channels: R (red), G (green), and B (blue). Input terminal supplied, 2
is an input terminal to which a vertically deflected sawtooth signal V is supplied; 3 is a first multiplier; 4 is an upper clip circuit;
5 is the second multiplier, 6 is the lower clip circuit, 7
R, 7G, 7B to 12R, 12G, 12B are provided three each corresponding to the R channel, G channel, and B channel, and 7
R, 7G, 7B are third multipliers, 8R, 8G, 8
B is the fourth multiplier, 9R, 9G, 9B, 10R,
10G, 10B are amplifiers, 11R, 11G, 11
B is an adder, and 12R, 12G, and 12B are vertical deflection devices.

Next, the operation of this embodiment will be explained.

The vertical deflection sawtooth signal V supplied from the input terminal 2 is input to the upper clipping circuit 4, and as shown in FIG. 2A, the portion Pu from its maximum value to a predetermined level is clipped and output as shown in FIG. 2B. The signal a ₁ shown in FIG. Similarly, the vertical deflection sawtooth signal V is also supplied to one input of the lower clip circuit 6, and as shown in FIG.
is clipped and the signal _a2 is extracted and supplied to one input of the second multiplier 5.

On the other hand, the other inputs of these multipliers 3 and 5 receive the horizontal deflection sawtooth signal H shown in FIG. 2C and G.
As a result, the output of the first multiplier 3 is the signal b ₁ shown in FIG. 2 D, and the output of the second multiplier 5 is the signal b ₂ shown in FIG. 2 H. You will be able to get it. In FIGS. 2A to 2H, 1V represents one vertical scanning period, and 1H represents one horizontal scanning period.

Therefore, this signal b ₁ is sent to the third multiplier 7R, 7
G, 7B is supplied to one input and multiplied by a DC control voltage Ra, Ga, Ba whose level can be arbitrarily adjusted over a predetermined range from positive polarity to negative polarity,
The output signals are set to predetermined levels by amplifiers 9R, 9G, and 9B to obtain correction signals R _c1 , G _c1 , and B _c1 .

Similarly, the output signal _b2 of the second multiplier 5 is supplied to one input of the fourth multiplier 8R, 8G, 8B, and the level is arbitrarily adjusted over a predetermined range from positive polarity to negative polarity. Possible DC control voltage Rb,
Gb and Bb are multiplied, and the multiplication output is sent to the amplifier 10R,
10G and 10B are amplified to a predetermined level to obtain correction signals R _c2 , G _c2 , and B _c2 .

Then, these correction signals are added to the adder circuit 11R,
11G and 11B, respectively, and then supply it to the corresponding vertical deflection devices 12R, 12G, and 12B,
It is superimposed on the vertical deflection signal to perform peripheral skew correction.

Therefore, it is now assumed that the control voltage Ra supplied to the third multiplier 7R is set to a positive voltage.

Then, the correction signal R _c1 appearing at the output of the amplifier 9R becomes a signal with a waveform as shown in FIG. As shown in FIG. 3B, on the imaging surface of the image pickup tube, the interval between the horizontal scanning lines becomes narrower in the left part of the lower predetermined range m, so the image changes from the broken line state as shown by arrow A. The image shrinks and becomes like a solid line, and on the left side, the interval between the horizontal scanning lines becomes wider, so the image extends as shown by arrow B and changes from a broken line to a solid line. At this time, the ratio between the amount of shrinkage on the left side indicated by arrow A and the amount of extension on the right side indicated by arrow B, that is, the magnitude of the inclination to the right side of the lower edge of the image plane, is determined by the control voltage Ra
It can be arbitrarily changed by the positive polarity voltage value.

Furthermore, if the polarity of the control voltage Ra is made negative, the correction signal R _c1 becomes as shown in FIG. 3. Therefore, in this case, the imaging surface of the R channel image pickup tube becomes as shown in FIG. 3D. The spacing between the horizontal scanning lines becomes wider on the left side of the lower predetermined range m, and narrows on the right side, so the image in this part extends as shown by arrow A on the right side and contracts as shown by arrow B on the right side. It turns out. The amount of tilt of the lower peripheral portion of the image plane to the left at this time can also be arbitrarily controlled by the negative polarity voltage value of the control voltage Ra.

Next, assume that the control voltage Rb supplied to the fourth multiplier 8R is set to a positive voltage. Then, the correction signal R _c2 appearing at the output of the amplifier 10R
becomes a signal with the waveform shown in FIG. 3E, which is supplied to the vertical deflection device 12R via the adder circuit 11R. As a result, on the imaging surface by the R channel image pickup tube, the signal is shown in FIG. 3F. As shown in FIG. As the distance between the lines becomes wider, the image extends from a broken line to a solid line, as shown by arrows B. At this time, the ratio between the amount of shrinkage in the left part indicated by arrow A and the amount of extension in the right part indicated by arrow B, that is, the amount of tilting of the upper edge of the image to the left, is controlled. It can be arbitrarily controlled according to the positive polarity voltage value of voltage Rb.

Furthermore, if the polarity of the control voltage Rb supplied to the fourth multiplier 8R is made negative, the waveform of the correction signal _Rc2 becomes as shown in FIG. On the imaging surface, as shown in FIG. 3H, in the predetermined range n on the upper side, the interval between the horizontal scanning lines increases on the left side, so the image extends from a broken line to a solid line as shown by arrow A. On the other hand, on the right side, the interval between the horizontal scanning lines becomes narrower, so the image changes from the broken line shown by the arrow B to the solid line, and eventually the control voltage Rb
The direction and amount of inclination of the upper peripheral portion of the image plane can be arbitrarily controlled according to the polarity and voltage value.

The above is an explanation of the imaging surface by the image pickup tube of the R channel, but the explanation is exactly the same for the other G channels and B channels, and the third multiplier 7G
By controlling the control voltage Ga supplied from the positive polarity to the negative polarity, the lower part of the imaging surface by the G channel image pickup tube can be changed as shown in Figure 3B or Figure 3D. , the control voltage of the fourth multiplier 8G can be changed as shown in FIGS. 3F and 3H. For the B channel as well, the image is arbitrarily changed as shown in FIG. 3B, D, F, and H by the control voltage Ba of the third multiplier 7B and the control voltage Bb of the fourth multiplier 8B. be able to.

Therefore, according to the above embodiment, the shape of the lower and upper portions of the imaging surface by the image pickup tube of each channel can be arbitrarily controlled independently of each other, regardless of the central portion. , it is possible to sufficiently perform registration correction on the entire image, including not only the central portion but also the lower and upper portions.

As explained above, according to the present invention, skew correction for the lower and upper parts of an image can be performed independently of each other and independently of the central part of the image, which is a drawback of the prior art. except for
Even when the image plane is accompanied by ladder-shaped distortion, it is possible to perform sufficient registration correction over the entire image plane, and to produce color television signals of excellent image quality without residual registration errors. It is possible to provide a peripheral vertical skew correction device for a television camera that can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the peripheral vertical skew correction device according to the present invention, Figs. 2 A to H are waveform diagrams for explaining the operation, and Figs. 3 A to H are waveform diagrams and images for explaining the effect. FIG. 1...Horizontal deflection sawtooth signal input terminal, 2...
...Vertical deflection sawtooth signal input terminal, 3...1st
multiplier, 4... upper clip circuit, 5... second
multiplier, 6...lower clip circuit, 7R, 7
G, 7B...Third multiplier, 8R, 8G, 8B...
... Fourth multiplier, 11R, 11G, 11B... Addition circuit, 12R, 12G, 12B... Vertical deflection device.

Claims (1)

[Claims] 1. In a vertical skew correction device that superimposes a sawtooth voltage synchronized with the horizontal deflection operation as a correction signal on the vertical deflection signal, The first and second sawtooth voltages are extracted by clipping the first and second sawtooth voltages, respectively.
a clip circuit, first and second multiplier circuits each having one input of these first and second sawtooth wave voltages and a horizontal deflection signal being supplied to the other input; third and fourth multiplier circuits each having one input of the output of the multiplier circuit and a DC control voltage whose voltage value changes over a predetermined positive and negative range being supplied to the other input; An adder circuit whose first and second inputs are the output of the fourth multiplier circuit is provided, and the output of the adder circuit is superimposed on the vertical deflection signal as the above-mentioned correction signal, thereby performing registration correction at the periphery of the image. A peripheral vertical skew correction device characterized in that it is configured to enable.