JPS59154890A - Color video camera - Google Patents

Abstract

PURPOSE:To obtain a negative/positive inverting circuit in common to the three systems of the NTSC, PAL and SECAM by applying a luminance signal for correcting white balance to a color difference signal from a demodulating circuit, and obtaining the color difference signal in response to the negative/positive inversion. CONSTITUTION:A chrominance carrier signal Sc separated at a separating circuit 12 is demoulated at demodulating circuits 13R, 13B and applied operating circuits 15R, 15B via LPFs 31R and 31B. A luminance signal DELTAY for correcting white balance is added at the operating circuits 15R, 15B and it is applied to negative/positive inversion switching circuits 32R, 32B. A switching signal SNP from a terminal 7 is applied to the negative/positive inverting switching circuits, and non-inverting signals, i.e., the color difference signals as they are obtained at the positive polarity and the phase of the color difference signals is inverted at the negative polarity. The color difference signal is supplied to the NTSC encoder 6 via LPFs 19R, 19B.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention with industrial application relates to a color video camera;
In particular, it has a function that can switch between outputting the color video signal obtained by shooting with the same polarity and outputting the luminance signal and color signal with each inverted. Involved.

Background technology and its problems If you take a picture using an optical camera button and record the image information content of the color negative film obtained by developing it on a VTR,
The advantage is that the image can be viewed on a color television receiver at any time without having to print it on photographic paper.

Therefore, a negative film is photographed using an adapter, the developed contents are made into a video image, and this is recorded on a VTR. In this case, since the colors of the color negative film are all complementary colors, it is necessary to invert the white and black levels of the luminance signal and to invert the phase of the color signal. Therefore, a color video camera is provided with a so-called negative/positive reversal switching function that performs this reversal operation and also outputs an output video signal without reversing when the color video signal is in a normal state.

FIG. 1 shows an example of a video camera having this negative/4-digital reversal switching function.

That is, in FIG. 1, (1) indicates a single-tube color image pickup tube, for example, of the Trinikon system (Trinicon is a registered trademark), and from this image pickup tube (1), a luminance signal sy and a carrier color Signal Sc (carrier frequency fsc is, for example, 5 M
Hz) and, for example, fI = 4.5 MHz c7) index signal SI is extracted, and this signal is connected to the serial 7' (2) and AGC amplifier 7'.
f3) to the low/'s filter (4), where the luminance signal SY is taken out. This signal SY is supplied to the NTSC encoder (6) via a negative/positive inversion switching circuit (5) equipped with a luminance signal. When outputting a signal with the same polarity as the multiple inputs to the negative/digital switching signal SNP (at 4?), and when outputting a signal with the polarity of the white level and black level reversed for the input (negative (time).

Also, the composite signal from the AGC amplifier (3) is supplied to the band/mother filter (former band/mother filter), and the carrier color signal SC and index signal SI are taken out.
, 8I are supplied to the separation circuit (1) and separated into signals Sc and SI.
13FL) (13B), and the index signal S is supplied to the demodulation circuit (13T) through the continuous wave forming circuit 04).
1. ) (13T1) and the signal Sc to 5QQ
kT (red and blue color difference signals of about z 5R-Y and 5B
-Y is demodulated and supplied to the arithmetic circuit 05R) (15B).

In addition, the luminance signal SY from the low/main filter (4) is supplied to the variable gain amplifier (xsR), and the control voltage ΔE for white balance adjustment is supplied to the variable gain amplifier (xsR) using, for example, a DC power supply (17R) and a variable resistor (1sT%). is formed, B is supplied to the amplifier (16R) as a gain control signal, and a luminance signal ΔY(-1(Δ<1)) for white balance correction is taken out from the amplifier (16TL). , the signal ΔY is supplied to the arithmetic circuit (1sR), and the signal ΔY is added or subtracted from the color difference signal 5R-Y to correct the white balance of the signal 5R-Y.
This corrected signal 5R-Y is passed through a color difference signal low/4' filter (19R) with relatively strict characteristics for carrier removal.
, ) to the NTSC encoder (6).

Regarding the color difference signal 5B-Y, the circuits (15B) to (18B
), the white balance is corrected in the same manner as the low/4' filter (19R), and is supplied to the N'l'SC encoder (6) through a low pass filter (19B) having the same characteristics as the low/4' filter (19R).

Then, a continuous wave signal Cs of the NTSC color subcarrier frequency of 3.58 MHz is supplied to the encoder (6) through the terminal /20, and an NTSC color video signal is obtained, which is sent to the synthesis circuit (8). A synchronizing signal from the synchronizing signal generating circuit (21) and a burst signal from within the burst signal generating circuit are added, and an NTSC composite color video signal is obtained at the output terminal (9).

In this case, the negative/positive inversion switching of the carrier color signal is performed by inverting or non-inverting the burst signal.

That is, the continuous wave signal C8 at the terminal (3.58M from 20) lz is supplied to the negative/positive inversion switching circuit (221).
In synchronization with the inversion switching circuit (5), the NP switches so that the signal C8 is taken out in the same phase during the digital signal, and the signal C8 is taken out with the phase inverted when the negative signal is used. And the output of the inverting switching circuit (221) is
2? fJ to form an intermittent burst signal, which is then supplied to an encoder (6).

The above is for a color video camera using the NTSC method, but not only the NTSC method, but also the PAL method, SECAM method, etc.
A color video camera that can be used for all three methods is being considered. This can be easily achieved by switching the encoder (6) and the following using each method.

However, switching between negative and positive is not easy. In other words, the configuration shown in Figure 1 can be used in common with all three systems for switching between negative and positive inversions for luminance signals, but when switching between negative and positive inversions for carrier color signals, the configuration shown in Figure 1 is used. This is because a method of inverting or non-inverting the phase of a burst signal is possible with the FAT method, but cannot be used with the SECAM method.

As a negative-positive inversion method for the non-usable carrier color signal common to these three methods, a method of inverting the continuous wave signal obtained from the index signal Sl can be considered.

That is, each output signal from the continuous wave forming circuit (15) is sent to the demodulation circuit (13) through an inversion switching circuit that outputs a negative/four-way switching signal (signals in the same phase when positive and out of phase when negative).
R) and (13B). However, in the case of such an inversion switching method, the color difference signal that is the output of the demodulation circuit (13R) (13B) is inverted and taken out when it is negative, so the luminance signal △ for white balance correction is Y must also be inverted and added when it is negative.

In other words, not only the inversion switching of the continuous wave signal for demodulation but also the inversion switching of the luminance signal ΔY for white balance correction would not last long and the configuration would be complicated. Further, in this case, since the frequency of the continuous wave signal for after-control is as high as 4.5 MHz, there is a drawback that a phase delay is likely to occur.

Furthermore, as a carrier color signal inversion switching method common to the three systems, a method of inverting the carrier color signal Sc from the separation circuit 02 can be considered, but in this case as well, the above-mentioned correction luminance signal ΔY is inverted and switched. Moreover, the drawbacks of difficulty in inversion without phase delay are undeniable.

Purpose of the Invention The present invention provides a color video camera having a negative/positive reversal switching function, in particular, as a negative/positive reversal switching circuit for color signal processing.
The purpose is to provide a device that can be commonly used in the three ECAM systems and is free from the aforementioned drawbacks.

Summary of the Invention This invention adds a luminance signal ΔY for white balance correction to the color difference signal from the demodulation circuit, and then obtains an inverted or non-inverted color difference signal from an inversion switching circuit according to negative/positive inversion. It is.

Embodiment Hereinafter, one embodiment of the present invention will be explained by taking as an example the case where it is applied to the above-mentioned color video camera.

FIG. 2 is an example of this, and the example shown in FIG. 2 is also a case where a color video signal of the NTSC system is obtained.

In this example, the output signals of the demodulation circuit (13R) and h (13B) in the example of FIG.
) and (31B) to the arithmetic circuit (15R) and (1
5B) K supplied. This loaf 4 filter (31R
) (31B) is a demodulation circuit (131'(,) (13
From B), fSC-fI = 5MHz -4,5MH
! = 500 kHz color difference signal as well as fsc
+ f■ = 5MHz + 4.5MT (z = = 9.5
Since unnecessary high frequency components of MHz can also be obtained, the rsc
+fIO This is for removing high frequency components. Therefore, it is a low/4' filter (1
9R, ) (19B) does not have to have strict characteristics.

In this way, the arithmetic circuits (15R,) and (15B) obtain a luminance signal ΔY for white balance correction on the color difference signal, which is a relatively low frequency signal, and this is used in the negative/positive inversion switching circuit (32FL). ) and (32B). A switching signal SNP is supplied to the negative/positive inversion switching circuits (32B) and (32B), and when the camera is in positive mode, the switching signal SNP is not inverted, that is, the color difference signal is obtained as it is.
When negative, the color difference signals are obtained with phase inversion. This inversion switching circuit (32TL) and (32F3)
The output of is supplied to the NTSC encoder (6) through loaf 4 filters (19R) and (19B) with strict characteristics for color difference signals. In this case, of course, there is no need to invert the burst signal, so the negative and four-way inverting switching circuit (22) in the example of FIG. The other components are the same as the example shown in FIG.

As described above, in this example, the color difference signal from the demodulation circuit is converted into a negative signal? Since it is inverted or non-inverted depending on the inversion, N
It is possible to switch between negative and tenon inversion for color signals common to T8C, PAL, and 8ECAM systems. Furthermore, after calculating the luminance signal △Y for white balance correction on the color difference signal from the demodulation circuit, negative/positive inversion switching is performed. No switching circuit is required. Furthermore, a demodulation circuit (13
B) Since a Lono bus filter is provided on the output side of (13B) to remove unnecessary high-frequency components, the signal inverted by the negative/positive inversion switching circuit (32R) and (32B) is a low-frequency signal of about 500kHz, for example. Since it is a color difference signal, the influence of phase delay during phase inversion is small.

FIG. 3 shows a main part of another example of the present invention, and in this example, the output stages of the demodulation circuits (13R) and (13B) are constructed of differential amplifiers. Therefore, from the demodulation circuit (13TL) and (13B), the color difference signal 5R-Y
5R-Y and signals 5R-Y and 8B-Y having opposite phases can be taken out, so these are utilized.

That is, the in-phase output 5R- from the demodulation circuit (13R,)
Y and negative phase outputs 5a-y are supplied to arithmetic circuits (15R1) and (15R2)K through low/4' filters (31Rt) and (31%), respectively, for removing unnecessary high-frequency components of fsC+f■. , while Anne f (16R)
The luminance signal ΔY for white balance correction is supplied to the arithmetic circuit (15Tt1), and the luminance signal ΔY for correction is inverted through the inverter (34R) and supplied to the arithmetic circuit (15R2). The outputs of these arithmetic circuits (15R1) (tsR2) are supplied to one and the other input terminals of a switch circuit (33R), and this switch circuit (33R) is switched by the negative/positive switching signal SNP. , this switch circuit (3
The color difference signal 5R-y from the arithmetic circuit (15R, 1) is obtained from the arithmetic circuit (15R, 1) when it is positive, and from the arithmetic circuit (15Ft) when it is negative.
2), an opposite phase color difference signal 5R-Y is obtained. The output of this switch circuit (33R) is then supplied to the encoder (6) through the low-thousand filter (19R).

The same is true for the blue color difference signal 5R-Y, and the demodulation circuit (13B) generates a multi-signal 8B-Y and a signal 5B with the opposite phase.
-Y is obtained, and these signals 5R-Y and 5a-y are filtered by low-thousand filters (31Bl) and (31B2), respectively.
) through the arithmetic circuit (15131) and (15B2)
△Y is supplied to the arithmetic circuit (15B1), and △Y is supplied to the arithmetic circuit (15B2) through the inverter (34B).
Y are respectively supplied, and the switch circuit (33
B) is switched by the switching signal SNP so that the outputs of the arithmetic circuits (15Bt) and (15B2) are selectively supplied to the low i9 filter (19B).

In this example, it can be said that the negative/positive inversion switching for the color signal is performed by switch circuits (33R) and (33B), and the negative/positive inversion switching for the color difference signal is also performed in this example. So NTSC.

It can be common to the three systems, PAL and SECAM. In this example, the demodulation circuit (13R) and (
Since negative/positive inversion is performed using the differential output from 13B), a circuit for inverting color difference signals is not required.

In addition, in this example, the switch circuit (33R) (33
Is the signal to be switched in B) low A? Sufilta (31R,
t) (31R2) (31Bt) (31B2), this switch circuit (3
3R, ) (33B) has the advantage that the leakage characteristics do not need to be strict and the switching speed does not need to be very high.

Effects of the Invention As described above, according to the present invention, since the color signal is switched from negative to digital at the color difference signal stage, there is a common problem among the three television systems, NTSC, PAL, and 8FiCAM.・Positive inversion switching circuit can be realized.

In this case, since signal inversion and switching are performed at the stage of one color difference signal, there is an effect that the influence of phase delay on inversion is small, and the leakage characteristics of the switch circuit do not have to be severe.

In addition, the luminance signal Δ for white balance correction is added to the color difference signal.
Since the negative/digital switching is performed after Y is calculated, there is also the effect that there is no need to switch the brightness signal for correction between negative and positive.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an example of a color video camera having a negative/positive inversion circuit, and FIG. 2 is a system diagram of an example of a color video camera having a negative/positive inversion circuit according to the present invention.
FIG. 3 is a system diagram of main parts of another example of the present invention. (13R) and (13B) are color difference signal demodulation circuits, (1
5R) and (15B) are arithmetic circuits for adding a luminance signal for white balance correction to the color difference signal, (31R) and (31B) are low-noise filters for removing high frequency components other than the color difference signal, ( 32R) and (32B) are negative/positive inversion switching circuits, and (33R) and (33B) are negative/digital inversion switching circuits.

Claims (1)

[Claims] In a color video camera having a function of switching between outputting a color video signal obtained by shooting in an inverted state and outputting the color video signal in a non-inverted state, When inverting or non-inverting the color signal of the video signal, a low/4' filter is provided on the output side of the color difference signal demodulation circuit to remove high frequency components other than the demodulated color difference signal, and this low pass filter An inversion switching circuit is provided at the subsequent stage, and the color difference signal from the low noise filter is supplied to the inversion switching circuit after a luminance component for white balance correction is added thereto. A color video camera in which an inverted or non-inverted color difference signal is selectively extracted in accordance with a switching signal, and this color difference signal is supplied to an encoder.