JPS597269B2 - color television camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color television camera that passes a subject image through a color stripe filter and forms the image on a photoelectric conversion surface to obtain a color television signal.

Color television cameras use a stripe filter to modulate two color components and demodulate colors by utilizing the correlation between adjacent horizontal scanning lines. occurs, color shift occurs at the vertical image edges, and the image quality deteriorates.

A conventional camera that has improved this drawback will be described.

As shown in Figure 1, a single-tube color television camera with a single frequency separation system has a white W-Yellow filter element in the vertical direction and a W-Y filter element so that the phase is reversed for each horizontal scanning line.
e White W provided overlapping obliquely with the filter element
- A filter consisting of a cyan Cy filter element is attached to the front of the image pickup tube. The signal obtained by scanning the dashed line of the image modulated by this filter is Ba()■ Y+
The signal obtained by scanning (R + B) sin ω is Sb
()■ Y+(R-B)sinω where Y is the low-frequency component and is the luminance signal, R is the red signal, B is the blue signal, and ω is the repetition frequency of the stripe filter expressed as the angular frequency. be.

Figure 2 shows the electrical configuration of a single frequency separation camera. 1 is an image pickup tube with a built-in stripe filter shown in Figure 1, 2 is a preamplifier, and 3 is modulation by the stripe filter. A luminance signal Y is obtained with an amplifier including a low-pass filter that removes the component.

Reference numeral 4 denotes an amplifier including a low frequency filter that matches the passbands of the R and B signals to obtain a luminance signal YL for the color difference signal.

5 is a band filter.

6 is a delay device that delays the output of the bandpass filter 5 by one horizontal scanning period, and 7 is an adder including an amplifier to obtain an R signal.

8 is a subtracter including an amplifier to obtain the B signal.

9 is a delay device for one horizontal scanning period, 10 is an adder, 11 is a matrix circuit for obtaining the color difference signal R-YL signal and B-YL signal, 12 is a balanced modulator, and 13 is a delay device for one horizontal scanning period. , 14 is an adder.

In this circuit configuration, the R signal is obtained from the adder 7, and the B signal is obtained from the subtracter 8, but since these R and B signals are generated by correlating signals delayed by one horizontal period, the R signal is , B signals are shifted in the vertical direction.

In order to correct this, similarly, the luminance signal YL for the color difference signal is passed through a delay device 9 that delays it by one horizontal period, and then added by an adder 10. In this way, color errors in image parts that change rapidly in the vertical direction can be improved to some extent.
``Now, as shown in FIG. 3, the black area 101,
When a modulation pattern that changes from a white part 102 to a black part 103 is projected onto the photoelectric conversion surface and is scanned, the signal during the vertical scanning period in which two screens are obtained is a luminance signal and a modulated signal as shown in Fig. 4A. The signals are superimposed.

The signal shown in FIG. 4C is obtained by delaying this modulation signal (shown at the beginning of FIG. 4) by one horizontal period. The R signal and B signal are obtained by adding and subtracting these two modulated signals. The waveform is shown in FIG. 4-2. At this time, a signal different from the current modulation pattern is generated with a delay of one horizontal period only in the portions changing from black to white and from white to black. As a means for correcting this, the luminance signal shown in FIG. Using this correction signal, the separated R and B signals are matrixed and corrected. However, if the portion 102 of the modulation pattern is white, or if it is of any color such as yellow, cyan, red, or blue, the correction cannot be satisfied. In addition, in the single frequency separation method, the input side signal and output side signal of the delay device 6 are added and subtracted to obtain the R signal and the B signal, but there is a certain relationship between the amplitude and phase of the input and output. There must be.

However, the attenuation amount and delay time of a delay device are generally affected by temperature and humidity. Then, a bead/)ζ of FH/2 (here, FH is the horizontal scanning frequency) is generated. In order to remove this FH/2 bead, the modulated color signal modulated by the balanced modulator 12 is further delayed by one horizontal scanning period, and the modulated color signal obtained through the delay device 13 and the modulated color signal that is not delayed are added to the adder 14. The bead component of FH/2 is removed. FIG. 6A shows the modulated color signal obtained by the balanced modulator 12, and the signal shown in FIG. As can be seen from this signal, the changing portion of the modulation pattern in FIG. 3 becomes a modulated color signal different from the original pattern over two horizontal periods. The present invention eliminates this drawback, and FIG. 7 shows one embodiment thereof.

Components designated by reference numerals 1 to 8 and 11 to 14 in the same figure are the same as those designated by the same reference numerals in FIG. 15 is a delay device that delays by one horizontal period, and 16 is a subtracter.

17 and 18 are adders, 19 and 20 are diodes, 21 is a phase inverter, and 22 is a gate circuit.

The subtracter 16 obtains the signal shown in FIG. 5C, and the adder 17,
In addition to 18, the R signal and B signal are corrected.

The output of the subtracter 6 is rectified by diodes 19 and 20, and one is inverted by a phase inverter 21 to obtain the gate signal shown in FIG. 6-2. This gate signal is applied to the gate circuit 22 to gate the modulated color signal for one horizontal period. Figure 6(e) shows the gated version of the modulated color signal in Figure 6(a). The figure shows this gated signal delayed by one horizontal period. This signal and the signal shown in Figure A are added together by an adder 14 to obtain the signal shown in Figure A. In this way, in the conventional system, the signal shown in FIG. 6C is obtained, but according to this embodiment, the signal shown in
As shown in the figure, it will be improved. For example, when a subject image changes from white to black, a color error conventionally occurs over two horizontal scanning periods, but in this embodiment, it occurs only during one horizontal scanning period.

Furthermore, when changing from black to white, conventionally a color error occurs over two horizontal scanning periods, but in this embodiment, the color error occurs during the first horizontal scanning period, and the color error occurs during the next horizontal scanning period. The hue does not change, only the amplitude decreases by 6ab. As is clear from the above embodiments, in a color camera that generally obtains color signals by utilizing the correlation between adjacent horizontal scanning lines, the modulated color signal is modulated by an encoder in order to remove the solid FH/2 bead mentioned above. However, according to the present invention, the color error can be reduced to one horizontal scanning line, resulting in a good result. It has the characteristic that it is possible to obtain television signals with high image quality.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a stripe filter, FIG. 2 is a block diagram of a conventional color television camera, FIG. 3 is a diagram showing an image pattern that causes color shift, and FIGS.
, and 6 are signal waveform diagrams, respectively. FIG. 7 is a block diagram of a color television camera according to one embodiment of the present invention. 1... Image pickup tube, 4... Amplifier including a low-pass filter,
6, 15, 13... Delay device, 7, 16, 14... Adder, 8... Subtractor, 22... Gate circuit.

Claims (1)

[Claims] 1. Optical means for forming an image obtained by modulating at least two color components with a stripe filter on a photoelectric conversion surface, and an electric signal obtained by scanning the photoelectric conversion surface using vertical correlation. means for processing and separating and demodulating a color signal corresponding to the modulated color component; modulation means for balanced modulating the color signal or color difference signal; and means for adding the signal delayed by one horizontal period; means for obtaining a difference signal between the luminance signal and a signal obtained by delaying the luminance signal obtained by separating it from the electrical signal by one horizontal period; and suppressing or blocking the modulated color difference signal delayed by one horizontal scanning period using the difference signal. A color television camera characterized in that it is equipped with means for: 2 The means for suppressing or blocking the difference signal includes a first circuit that passes only one polarity of the difference signal, a second circuit that passes only the other polarity, and a third circuit that inverts the polarity of the output of the second circuit. A fourth circuit that generates a gate signal by combining the outputs of the first and third circuits, and a circuit that gates the modulated color difference signal using the gate signal. The color television camera described in paragraph 1. 3. Optical means for forming an image on a photoelectric conversion surface obtained by modulating at least two color components with a stripe filter, and processing the electrical signal obtained by scanning the photoelectric conversion surface using vertical correlation to obtain the above-mentioned modulation. means for separating and demodulating a color signal corresponding to the color component, means for balanced modulating the color signal or color difference signal, means for adding the modulated signal and a signal delayed by one horizontal period; means for obtaining a difference signal between a luminance signal separated from the signal and a signal obtained by delaying this by one horizontal period; and a means for obtaining an error portion of the demodulated color signal using this difference signal or a signal whose polarity and amplitude are controlled. A color television camera comprising means for compensating, and means for suppressing or blocking the modulated color difference signal delayed by one horizontal period using the difference signal.