JP2603363B2 - Luminance / color signal separation circuit - Google Patents

Description

The present invention relates to a television receiver using a charge transfer element (hereinafter, referred to as “CCD”) that works for delaying one horizontal period (hereinafter, referred to as “1H”). The present invention relates to a luminance / color signal separation circuit such as a video tape recorder.

2. Description of the Related Art Conventionally, such a luminance / color signal separation circuit is configured as shown in FIG. 2, and a color video signal supplied to an input terminal (1) is supplied to a path (2) of 3.58 MHz. In addition to being input to the operation filter (4) through the band-pass filter (3), a 3.58 MHz band delayed by 1H by the first CD (5) and provided in the low-pass filter (6) and the path (7) After being supplied to the operation filter (4) through the pass filter (8) and further delayed by 1H from the low-pass filter (6) by the second CCD (9), it is provided to the low-pass filter (10) and the path (11). 3.58MHz
Is supplied to the operation filter (4) through the band pass filter (12).

Here, the arithmetic filter (in this case, a logical comb filter) (4) has three paths (2) and (7) with 0H, 1H, and 2H delay.
The color signal from (11) is input, the vertical correlation is calculated, and an appropriate color signal is output. Then, this output is guided to a chroma processing circuit (13) and processed (extracting the original color difference signal), and further added to an adder (14).
Here, only the luminance signal is extracted by being combined with the output of the low-pass filter (6).

In order to operate the CCDs (5) and (9), a clock for transfer timing is required. This clock is generated by the chroma processing circuit (13) based on the color burst signal from the arithmetic filter (4). The clock of 3.58 MHz obtained is multiplied by 4 by a multiplier (15). Here, the multiplier (15) is a voltage-controlled oscillator (16) that outputs an oscillation frequency of 3.58 MHz multiplied by 4, and the oscillation output of the voltage-controlled oscillator (16) is divided by 1 / n. Divider to divide (17)
Phase comparison between the frequency-divided output of the frequency divider (17) and the 3.58 MHz clock from the chroma processing circuit (13) to supply a control voltage for oscillation output control to the voltage-controlled oscillator (16) (18).

However, in the luminance / color signal separation circuit having the conventional configuration, the chroma processing circuit (13) converts the color signal based on the color burst signal that has passed through the CCDs (5) and (9). Since processing and clock generation are performed, even when a video signal that does not include, for example, a color burst signal is applied to the input terminal (1), the CCD
(5) The transfer timing clocks of (9)
Leakage from the CCDs (5) and (9) is input to the arithmetic filter (4) and supplied to the chroma processing circuit (13) from the arithmetic filter (4), so that the color killer does not work properly in the chroma processing circuit (13). , A clock having a frequency shifted from 3.58 MHz is generated to cause the multiplier (15) to perform erroneous phase control. As a result, if the output frequency of the multiplier (15) is further shifted, the clock for the transfer timing is greatly shifted. Therefore, when the video signal including the color burst signal is input next, the transfer clock is changed. Takes a long time to return to the normal frequency, which may cause an undesired color image to be reproduced for a while.

The present invention has been made in view of such a point, and the CC
It is an object of the present invention to provide a luminance / color signal separation circuit in which a chroma processing circuit performs a stable operation without being affected by the leakage of a clock for D transfer timing.

Means for Solving the Problems In order to achieve the above object, according to the present invention, after a color video signal is delayed via a CCD serving as a 1H delay, the color filter is combined with a different color video signal temporally in 1H units by an arithmetic filter. A luminance / color signal separation circuit which separates and extracts a color signal by performing a color burst signal which does not pass through the CCD to a clock generation circuit which forms a clock signal to be applied to the CCD based on the color burst signal. And a color burst supply circuit for supplying the color signal from the arithmetic filter and the CC.
A switching means for selectively switching between a color burst signal in a color video signal which does not pass through D, while the clock generation circuit receives the output of the switching means, processes the color signal, and performs color burst frequency processing. And a multiplier for multiplying the clock from the chroma processing circuit. Further, the color burst supply circuit includes a signal angle adjusting means for temporally matching the color video signal with the color signal from the arithmetic filter on a path for supplying the color video signal to the switch. Is what it is.

According to such a configuration, the clock to be applied to the 1H delay CCD is formed by the clock generation circuit based on the color burst signal from the color burst supply circuit that does not pass through the CCD. The color signal from the arithmetic filter is supplied to the clock processing circuit that constitutes the clock generation circuit, but the color burst signal from the color burst supply circuit is supplied only during the color burst signal period of the color signal. It will be supplied by the switch means.

An embodiment of the present invention will be described below with reference to the drawings. The same parts as those in the related art are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, as shown in FIG. 1, the CCDs (5) and (9) pass through a clock generation circuit (19) composed of the above-mentioned chroma processing circuit (13) and a multiplier (15). A color burst supply circuit (20) for supplying a color burst signal is provided. Specifically, a color signal from the arithmetic filter (4) and a color video signal not passing through the CCDs (5) and (9) are provided. A switch circuit (21) for selectively switching between a color burst signal and an intermediate color burst signal is provided. A color signal from the arithmetic filter (4) is supplied to one of the switching terminals (21a) of the switch circuit (21), and the other is provided. Switching terminal (21
A color burst signal extracted from the color video signal before passing through the CCDs (5) and (9) is supplied to b). The color video signal supplied to the input terminal (1) is 3.58.
After extracting only the color signal through the MHz band pass filter (22) and inverting and amplifying by the inverting amplifier circuit (23),
The angle is adjusted by an angle adjusting circuit (24) so as to match the color signal from the arithmetic filter (4) in time, and is supplied to the switching terminal (21b). The switch circuit (21) is connected to the switching terminal (21) only during the period of the color burst signal of the color signals from the operation filter (4).
A switching pulse is applied to its control terminal (21c) so as to switch to the b) side. The gate pulse generator (26) is formed based on the synchronizing signal extracted in (1).

Therefore, the color signal from the arithmetic filter (4) is supplied to the chroma processing circuit (31) through the switch circuit (21), and the color burst is supplied only during the color burst signal period of the color signal. The color burst signal from the circuit (20) will be supplied. As a result, the chroma processing circuit (13) generates a 3.58 MHz clock based on the color burst signal that does not pass through the CCDs (5) and (9), processes the color signal from the arithmetic filter (4), Stable operations such as ACC (automatic color control) and APC (automatic phase control) are performed.
When a video signal that does not include a color burst signal is applied, the 3.58 MHz clock output from the chroma processing circuit (13) has a free oscillation frequency and is applied to the multiplier (15). Will be.

According to the luminance / color signal separation circuit of the present invention as described above, the CCD has excellent luminance / color separation capability by CCD,
In addition, stable processing of a color signal and formation of a clock to be applied to a CCD can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a circuit configuration for realizing the present invention;
FIG. 2 is a diagram showing an example of a conventional circuit configuration. (4) Operation filter, (5) (9) CCD, (13) Chroma processing circuit, (15) Multiplier, (19) Clock generation circuit, (20) Color Burst supply circuit, (21) ... Switch circuit.

Claims (2)

(57) [Claims] A color signal is separated by delaying a color video signal through a charge transfer element serving for one horizontal period delay, and then combining the color video signal with a different color video signal in a unit of one horizontal period with an arithmetic filter. And a clock generation circuit that forms a clock signal to be applied to the charge transfer element based on a color burst signal.
In a luminance / color signal separation circuit provided with a color burst supply circuit for supplying a color burst signal that does not pass through the charge transfer element, the color burst supply circuit includes a color signal from the operation filter and a color that does not pass through the charge transfer element. The clock generating circuit receives an output of the switch and processes a color signal and generates a clock of a color burst frequency. A luminance / color signal separation circuit including a chroma processing circuit and a multiplier for multiplying a clock from the chroma processing circuit. 2. A color burst supply circuit according to claim 1, wherein said color burst supply circuit includes a signal angle adjusting means for temporally matching said color video signal and a color signal from said arithmetic filter to a path for supplying said color video signal to said switch. The luminance / color signal separation circuit according to claim 1, wherein the luminance / color signal separation circuit includes: