JPS59127496A - Color television camera - Google Patents

Abstract

PURPOSE:To invert the polarity of a chrominance signal to positive polarity without causing any hue shift by generating a pulse signal for modulating a subcarrier and the inverted signal of the pulse signal to produce a color burst signal. CONSTITUTION:A burst generating circuit 15 imposes balanced modulation upon a color subcarrier SC obtained by a chrominance subcarrier generating circuit 5 by a burst flag pulse BF or a pulse BF passed through an inverter 23 to generate the color burst signal. This color burst signal is added by an adding circuit 13 to the output signal of an adding circuit together with a composite synchronizing signal obtained by a synchronous generating circuit 4 through a phase adjusting circuit 16. Consequently, a negative color burst signal is accurately 180 deg. out of phase with a positive color burst signal, so the chromaticity signal of a color TV signal obtained by the adding circuit 13 is inverted in polarity accurately. In this case, the circuit 16 adjusts phase shift generated by balanced modulating circuits 8 and 9 to invert the polarity of the chromaticity signal accurately.

Description

Detailed Description of the Invention (Technical Field) The invention of this application relates to a color television camera.

(Prior Art) A color television camera has been proposed that has a function of reversing the polarity of the television signal obtained by imaging and outputting it. , Example: This type of camera can not only be used as a normal television camera, but also produce color television directly from photographic negatives or 8mm negative film by reversing the polarity of the television signal with a switch or the like. It can also be used as a camera that obtains signals, a so-called telecine camera.

FIG. 1 is a diagram showing an example of a conventional color television camera as described above. 1 is an imaging unit, which has red (R), green (
It outputs three color signals: G) and blue (B). R, G, B
are respectively supplied to the matrix circuit 2, and the matrix circuit 2
The luminance signal (Y) and two color difference signals (R-Y and B-Y
) is obtained.〇On the other hand, the high frequency oscillation signal oscillated by the reference oscillation circuit 6 drives the imaging section 1 and the synchronization generation circuit 4.
and is supplied to a color subcarrier generation circuit 5. This color subcarrier (hereinafter referred to as SC)
The one whose phase is shifted by -90° by the -90° phase shift circuit 6 is R-Y.
Balanced modulation is performed by the balanced modulation circuit 8 according to the following. Also -90
The output of phase shift circuit B is further -90 degrees by phase shift circuit 7.
The phase-shifted signal, that is, the SC phase-shifted by 180 degrees, is balanced-modulated by B-Y in a balanced modulation circuit 9. These modulated signals and Y are added in an adder circuit 10.

12 is a changeover switch, and the output signal of the adder circuit 10 is supplied to the P side terminal in the figure, and the inverted version of that signal is supplied to the N side terminal in the figure through the inverting amplifier 11. It is supplied to the adder circuit 13.

The composite synchronization signal (including a vertical synchronization signal and a horizontal synchronization signal) obtained by the synchronization generation circuit 4 is supplied to an adder circuit 13 and also to a pulse generation circuit 14 . The pulse generating circuit 14 generates a burst flag pulse (hereinafter referred to as BF) for producing a color burst signal at a timing corresponding to the back porch portion within the horizontal retrace period. The BF obtained by the pulse generation circuit 14 is sent to the color burst generation circuit 15.
By doing so, a color burst signal is obtained from the color burst generation circuit 15.However, if the color burst signal obtained from the color burst generation circuit 15 is used as it is, the SO is balanced modulated by the balanced modulation circuits 8 and 9.
Also, phase shift and color shift of color signals caused by the inverting amplifier 11 occur. Therefore, the color burst generation circuit 15
It is necessary to adjust the phase of the color burst signal obtained in . In this adjustment, the output signal of the adder circuit 10 is directly applied to the adder circuit 1.
6, that is, when trying to obtain a normal color television signal (hereinafter referred to as positive time), the phase shift caused by the balanced modulation circuits 8 and 9 is compensated for, and the output signal of the adder circuit 10 is inverted. When supplying the signal to the adder circuit 13 via the amplifier 11, that is, when trying to obtain a color television signal with reversed polarity (hereinafter referred to as negative time), the phase generated by the balanced modulation circuits 8 and 9 and the inverting amplifier 11 is I'll adjust the discrepancies. The switch 18 is a switch that is connected to the N side terminal in the figure when it is negative, and to the P side terminal in the figure when it is positive.In other words, the phase adjustment circuit 16 adjusts the above-mentioned phase shift when it is positive, and adjusts the phase vI4. 't1.
The circuit 17 is a circuit that adjusts the phase shift when negative.

In the adder circuit 16, the adder circuit 10 via the inverting amplifier 11
Adding circuit 1 that does not go through the output signal of or inverting amplifier 11
The composite synchronization signal obtained by the synchronization generation circuit 4 and the color burst signal whose phase has been adjusted as described above are added to the output signal of zero. The power 2-television (l) thus obtained by the adder circuit 16 is output from the terminal 19.

In the above-mentioned configuration, a circuit is required to individually adjust the above-mentioned phase shift both in the negative state and in the positive state. This circuit requires strict adjustment, and the circuit itself is complicated. Further, complete adjustment may not be possible due to characteristic fluctuations due to temperature characteristics of the inverting amplifier 11, the balanced modulation circuits 8 and 9, and the inverting amplifier 11, and hue deviations may occur due to this.

(Purpose) The first invention of this application prevents hue shift due to the inversion when the polarity of a television signal is inverted and output.
It is an object of the present invention to provide a color television camera that can omit circuits such as a phase adjustment circuit.

In addition to the above-mentioned object, the second invention of this application also provides a method for reversing the polarity described above.
The objective is to provide a color television camera capable of preventing this problem without providing a special phase adjustment circuit.

(Example) The invention of this TK3 application will be described in detail below using Examples. The citation of the following examples does not limit the scope of the invention of this application, and the invention of this application can be modified as appropriate within the scope of the above-mentioned claims.

FIG. 2 is a diagram showing the configuration of a color television camera as an embodiment of the invention of this application.

Components similar to those of the camera in FIG. 1 are given the same numbers.

Y obtained in the matrix circuit 2 is P of the switch 21 in the diagram.
The polarity of Y is inverted by the inverting amplifier 20 and is supplied to the illustrated N side terminal of the switch 21. Switch 21 is N 9i1 terminal when negative, P when positive
When the adder 10 is positive, the normal Y is connected to the side terminal, and when the adder 10 is positive, the polarity of the Y is inverted, and when the adder 10 is positive, the polarity of the Y is inverted and balanced modulated by the balanced modulators 8 and 9.
and B−Y.

The signal obtained by the adder 10 in the negative state has only the polarity of Y reversed, and the chromaticity signal is the same as the chromaticity signal in the positive state.

-The BF obtained by the 10,000-pulse generation circuit 14 is supplied to the color burst generation circuit 15 as is when it is positive, and with its polarity reversed when it is negative. Here, 23 is an inverter, and the switch 22, like the switch 21, is a switch that is connected to the N-side terminal shown in the figure in the negative state and to the P-side terminal in the figure in the positive state. Since BF is a pulse signal, the polarity can be easily reversed using the inverter 26.

In the color burst generation circuit 15, the SC obtained by the color subcarrier generation circuit 5 is balanced-modulated by the BF or the BF via the inverter 26, thereby obtaining a color burst signal. Here, a color burst signal obtained by balanced modulation with a BF whose polarity is inverted via an inverter 23;
The color burst signal obtained by balanced modulation using BF without going through the inverter 23 has a phase difference of exactly 180°. The color burst signal obtained in this manner is passed through the phase adjustment circuit 16 together with the composite synchronization signal obtained by the synchronization generation circuit 4 to the addition circuit 1 described above.
Add it to the output signal of 0.

With this shift, the phase of the color burst signal in the negative mode is exactly 180 degrees different from that in the positive mode, so the chromaticity signal of the color television signal obtained by the power multiplication circuit 13 has exactly reversed polarity. There will be. The phase adjustment circuit 16 is a circuit for adjusting the phase shift occurring in the balanced modulation circuits 8 and 9. According to the above configuration, the phase of the color burst signal can be accurately changed by 180° by reversing the polarity of the BF. Therefore, the polarity of the chromaticity signal can be accurately inverted. Therefore, there is no concern that a phase shift of the chromaticity signal will occur due to polarity reversal, and there is no need to provide a phase adjustment circuit for this purpose, which simplifies the circuit. Also, in this case, regardless of the temperature, the color burst signal is accurately 18 in both negative and positive conditions.
Since the difference is 0°, the polarity of the chromaticity signal is accurately reversed regardless of temperature changes.

FIG. 6 is a diagram showing a color television camera as another embodiment of the invention of this application. Components similar to those of the color television camera in FIG. 2 are given the same numbers.

Reference numeral 25 denotes a changeover switch, which is connected to the N-side terminal in the figure when negative, and to the P-side terminal in the figure when positive.

The BF obtained from the pulse generation circuit 14 is inverted by the inverter 26 when it is negative and is inverted by the inverter 26 when it is positive.
is supplied to In the adder circuit 27, this pulse signal and BY obtained in the matrix circuit 2 are added. Since the color burst signal and B-Y are specified to have opposite phases to each other, when a signal obtained by shifting the color subcarrier by -180°, which is balanced-modulated by B-Y, is balanced-modulated by BF, it becomes a normal color burst signal. A color burst signal with the opposite phase is obtained, and when the BF is balanced-modulated with a pulse signal inverted, a color burst signal with the same phase as when the color subcarrier is balanced-modulated with the BF is obtained. Therefore, the balanced modulation circuit 9'
The signal obtained in the positive state is balanced modulated B-Y
and a color burst signal with a normal phase, and in the negative mode, a balanced modulation BY and a color burst signal with a phase opposite to the normal one.

The output signal of the balanced modulator 9' is multiplied by the balanced modulations RY and Y in an adder circuit 10'. However, Y is a signal whose polarity is inverted when negative, as in the example of FIG. 3 described above.

The output signal of the adder circuit 10' is added with a composite synchronization signal in the adder circuit 16', and is outputted from the output terminal 19 as a color television signal. It is possible to accurately phase invert the chromaticity signal. Further, since BF and the signal obtained by inverting BF are subjected to balanced modulation in the same circuit as B-Y, there is no fear that a phase shift with B-Y or R-Y will occur, and there is no fear that a hue shift will occur. Also, the temperature characteristics of the modulator are not a problem. Therefore, there is no need to provide a phase adjustment circuit for compensating for hue shifts due to signal phase shifts.

(Effects) As explained above using the embodiments, the first inventor of this application produces a color television signal using a signal obtained by inverting a pulse signal for modulating color subcarriers to create a color burst signal. Since the polarity of is reversed, there is no hue shift due to reversal. Furthermore, there is no need to provide a special circuit to compensate for the hue shift caused by the inversion.

Further, in addition to the above-described effects, the second invention of this application modulates the pulse signal by adding it to the color difference signal, so that the hue shift that normally occurs due to modulation does not occur. Further, there is no need to provide any circuit for compensating for hue deviation.

[Brief explanation of the drawing]

Fig. 1 shows an example of a conventional color television camera, Fig. 2 shows a color TV camera as an embodiment of the present invention, and Fig. 6 shows another embodiment of the invention. FIG. 2 is a diagram showing a color television camera. 5 is a color subcarrier generation circuit, 14 is a pulse signal generation circuit,
15 is a color burst signal generation circuit, 22 is a changeover switch, 26 is an inverter, 25 is a changeover switch as selection means, 26 is an Fi inverter, and 27 is an addition circuit as addition means.

Claims (1)

[Claims] 1) A camera that generates a color television signal, comprising means for generating a pulse signal that modulates a color subcarrier and an inverted signal of the signal to create a color burst signal. Color television camera. 2) A camera that generates a color television signal, comprising generating means for generating a pulse signal that modulates a color subcarrier to create a color burst signal and an inverted signal of the signal, and said pulse signal and said inverted signal. 1. A color television camera comprising: a selection means for selecting one of the signals, and an addition means for adding the pulse signal obtained by the selection means and a predetermined color difference signal.