JPH0575239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a comb filter circuit suitable for use in separating luminance signals and color signals in a reproduction system of a PAL color video tape recorder.

[Summary of the invention]

The present invention applies to a comb filter circuit used to separate luminance signals and chrominance signals in the reproduction system of a PAL color video tape recorder, for example, in which the reproduced luminance signals and the reproduced chrominance signals are separated in frequency bands. The mixed signal is supplied to a two-horizontal period delay line of the charge transfer type, and the luminance signal is a one-horizontal signal extracted from the one horizontal period delay point of the two-horizontal period delay line of the charge transfer type. Crosstalk components between the period delayed signal and the luminance signal are removed, and the luminance signal is separated through a low-pass filter, and the chrominance signal is output from the mixed signal and the charge transfer type two-horizontal delay line. By removing the crosstalk components of the 2-horizontal period delayed signal and the chrominance signal and separating the chrominance signal using a band-pass filter, the 2-horizontal period delay line is used for playback on, for example, a PAL color video tape recorder. This allows a comb filter circuit used in the system to be configured.

[Conventional technology]

Conventionally, for example, the crosstalk of the raw luminance signal in the comb filter circuit used to separate the luminance signal and color signal in the playback system of a PAL color video tape recorder is 1/2 h (h is the horizontal frequency) with respect to the main signal. ) A comb-shaped filter circuit as shown in Figure 3 has been proposed as a comb filter circuit that separates the luminance signal and chrominance signal from the reproduced signal by interleaving the main signal by 1/4 h and interleaving the reproduced chromaticity signal. ing. That is, in FIG. 3, 1Y indicates a reproduced luminance signal input terminal to which a PAL system reproduced luminance signal is supplied, and 1C indicates a reproduced color signal input terminal to which a PAL system reproduced color signal is supplied. The terminal 1Y is connected to one input terminal of the subtraction circuit 2, and the reproduced luminance signal input terminal 1Y is connected to a charge transfer type circuit 1 made of a CCD, for example.
Connected to one input terminal of the subtraction circuit 4 via the horizontal period delay line 3, and further connected this reproduced luminance signal input terminal 1Y to the other input terminal of the subtraction circuit 4,
The output terminal of this subtraction circuit 4 is connected to the other input terminal of the subtraction circuit 2 via a limiter circuit 5, and the output terminal of this subtraction circuit 2 is connected to a luminance signal output terminal 6Y.
Derive. In this case, since the crosstalk components of the reproduced luminance signal are interleaved in relation to the 1/2h line offset frequency during recording, the crosstalk components can be removed using a comb filter circuit using a delay line 3 of one horizontal period. can.

Also, the reproduced color signal input terminal 1C is connected to one input terminal of the subtraction circuit 7, and the reproduced color signal input terminal 1C is connected to the other input terminal of the subtraction circuit 7 via a charge transfer type, for example, a delay line 8 of a CCD with two horizontal periods. The color signal output terminal 6C is derived from the output terminal of the subtraction circuit 7. In this case, since the crosstalk components of the reproduced color signal are interleaved at the 1/4h offset frequency during recording, the crosstalk components can be removed by a comb filter circuit using a delay line 8 of two horizontal periods.

[Problem that the invention seeks to solve]

The comb filter circuit used to separate the luminance signal and chrominance signal in the playback system of a conventional PAL color video tape recorder has three delay lines: a delay line 3 for one horizontal period and a delay line 8 for two horizontal periods. When a delay line for a horizontal period is required and this delay line is constructed from a charge transfer type CCD, for example, there is a disadvantage that the number of elements increases and the mounting space increases accordingly.

In view of this, an object of the present invention is to configure a comb filter circuit used to separate the luminance signal and color signal in the reproduction system of a PAL color video tape recorder, for example, from a delay line for two horizontal periods. shall be.

[Means for solving problems]

In the present invention, as shown in Fig. 1, the crosstalk of the reproduced luminance signal is 1/2h (h is the horizontal frequency) with respect to the main signal.
The reproduced luminance signal and the reproduced chrominance signal are interleaved and the reproduced chrominance signal is interleaved in a comb filter circuit that separates the luminance signal and chrominance signal from the reproduced signal by 1/4h interleaving with respect to the main signal. The mixed signals, which are separated in frequency bands and mixed together, are supplied to the charge transfer type delay lines 9 and 10 with two horizontal periods, and the luminance signal is transmitted between the mixed signal and the charge transfer type delay line with two horizontal periods. 9,1
The crosstalk component of the luminance signal is removed from the 1 horizontal period delayed signal extracted from the 1 horizontal period delay point 9 of 0, and the luminance signal is separated through the low pass filter 11, and the chrominance signal is obtained by combining this mixed signal and this signal. Charge transfer type delay line 9, 1 with two horizontal periods
Crosstalk components of the color signal are removed from the two-horizontal period delayed signal obtained on the output side of 0, and the color signal is separated through a band pass filter 12.

[Effect]

According to the present invention, since a charge transfer type delay line with two horizontal periods can be used to separate both the luminance signal and the color signal, this comb filter circuit can be replaced with a charge transfer type delay line with two horizontal periods. Can be configured.

〔Example〕

An embodiment of the comb filter circuit of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

PAL supplied to playback brightness signal input terminal 1Y
The reproduced luminance signal of the reproduction system of a color video tape recorder of this type is supplied to one input terminal of the adder circuit 14 through a low-pass filter 13 that passes only the reproduced luminance signal, for example, 4 MHz or less, and is also supplied to one input terminal of the adder circuit 14. 1C is supplied to the other input terminal of the adder circuit 14 through a band pass filter 15 that passes only the reproduced color signal, for example, a 4.43 MHz signal. . This adder circuit 14 mixes the reproduced luminance signal and reproduced color signal separated in frequency bands. This mixed signal obtained at the output side of the adder circuit 14 is transferred to a charge transfer type, for example.
The signal is supplied to the input side of the delay line 9 of a series circuit consisting of two delay lines 9 and 10 of one horizontal period each made up of CCDs. Further, a mixed signal of the reproduced luminance signal and the reproduced color signal obtained at the output side of the adder circuit 14 is supplied to the input terminal of the adder circuit 17 via a 1/2 attenuator 16 that halves the signal level. The output signal of the delay line 9 from which a horizontal period delayed signal is obtained is supplied to the input terminal of this adder circuit 17, and the signal level of the signal delayed by two horizontal periods obtained at the output side of the delay line 10 is reduced to 1/1. 1/2 attenuator 1 to 2
8 to the input terminal of the adder circuit 17, and the output terminal of the adder circuit 17 is supplied with a 1/2 attenuator 19 which halves the signal level, and a low pass which passes only the frequency of the luminance signal, for example, 4 MHz or less. Brightness signal output terminal 6 via a series circuit of filter 11
Connect to Y. In this case, the mixed signal of the reproduced luminance signal and the reproduced color signal, the one horizontal period delayed signal, and the two horizontal period delayed signal are added in the adder circuit 17 in a predetermined level relationship. The transfer function H(Z) of the reproduced luminance signal at this time is H(Z) = 1/4 (1 + Z ^-1 ) ² = Z ^-1 /4 (Z ⁺¹ +2 + Z ^-1 ), and the delay line for one horizontal period is Equal to the characteristics when passed twice through a comb filter circuit using
Also, the delay time is equal to Z ^-1 . Therefore, adder circuit 1
In the output signal No. 7, the crosstalk component of the reproduced luminance signal is removed as in FIG. 3, but the reproduced color signal and its crosstalk component are included. By passing the output signal of the adder circuit 17 through a low-pass filter 11 that passes only the frequency signal of the luminance signal, only the luminance signal can be separated.

Further, a mixed signal of the reproduced luminance signal and the reproduced color signal obtained at the output side of the adder circuit 14 is supplied to one input terminal of the subtractor circuit 20, and the signal delayed by two horizontal periods obtained at the output side of the delay line 10 is supplied to the other input terminal of this subtraction circuit 20, and the output terminal of this subtraction circuit 20 is supplied with a 1/2 attenuator 21 which reduces the signal level to 1/2, and passes only the frequency signal of the color signal, for example, a 4.43MHz signal. color signal output terminal 6C via bandpass filter 12.
Connect to. In this case, the reproduced color signal is a mixed signal of the reproduced luminance signal and the reproduced color signal, and this two horizontal period delayed signal is subtracted by the subtraction circuit 20, and the crosstalk component of this color signal is removed as in the conventional case.
The transfer function H(Z) at this time is H(Z) = 1/2 (1-Z ^-2 ) = Z- ¹ /2 (Z ⁺¹ - Z ^-1 ), and the delay time is Z ^-1. . This subtraction circuit 2
Since the output signal of 0 includes not only the color signal but also the high frequency part of the reproduced luminance signal, this output signal is passed through the bandpass filter 12 that passes only the frequency of the color signal, and the color signal is output to the color signal output terminal 6C. Only the signal can be separated and obtained.

As described above, according to this example, the reproduced luminance signal and the reproduced chrominance signal are limited to their respective bands and mixed before being passed through the delay line. A comb filter circuit that can separate both color signals can be obtained. Therefore, when this delay line is constructed using a charge transfer type, for example, a CCD, the number of elements is reduced accordingly, which is advantageous in terms of cost, mounting space, etc. Furthermore, in the above example, the delay times of the luminance signal and color signal can be matched, and the luminance signal system is also a comb filter circuit using two horizontal period delay lines 9 and 10, improving the S/N of the color video signal. can.

Further, FIG. 2 shows another embodiment of the present invention, and this FIG. 2 shows an example in which the comb-shaped filter circuit of the luminance signal system of the example of FIG. 1 is made into a dynamic type. This second
In explaining the figures, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

In the example shown in FIG. 2, the one horizontal period delayed signal obtained at the output side of the delay line 9 is supplied to the input terminal of the subtraction circuit 22, and the mixed signal obtained at the output side of the addition circuit 14 is supplied to the 1/2 attenuator 16. The signal delayed by two horizontal periods obtained at the output side of the delay circuit 10 is supplied to the negative terminal of the subtractor circuit 22 via the 1/2 attenuator 18, The output signal of the circuit 22 is supplied to one input terminal of the subtraction circuit 5 via a 1/2 attenuator 19, a low-pass filter 23 that passes the frequency of the luminance signal, for example, 4 MHz or less, and a limiter circuit 24 that limits the amplitude. The one horizontal period delayed signal obtained at the output side of the delay line 9 is supplied to the other input terminal of the subtraction circuit 25 through a low-pass filter 26 that passes the frequency of the luminance signal, for example, 4 MHz or less, and the output terminal of the subtraction circuit 25 is is connected to the luminance signal output terminal 6Y. The rest of the structure is the same as in FIG. 1.

In FIG. 2, in the subtraction circuit 22, the reproduced luminance signal, the mixed signal of the reproduced signal, its one horizontal period delayed signal, and its two horizontal period delayed signals are output to this output terminal. A signal of the chrominance signal + the crosstalk component of the chrominance signal is obtained, and this signal is supplied to the low-pass filter 23, and only the crosstalk component of the luminance signal is obtained at the output side of this low-pass filter 23. The crosstalk component of the luminance signal is supplied to the subtraction circuit 5 via the limiter circuit 24, and the reproduced luminance signal delayed by one horizontal period, that is, the luminance signal + the crosstalk component of the luminance signal, is supplied to the output side of the low-pass filter 26. A signal of
Only the luminance signal can be obtained in Y. In this case, the crosstalk component of the luminance signal is transferred to the limiter circuit 24.
Since the amplitude is limited by , it is possible to obtain a characteristic in which the pass band of the comb filter circuit of this luminance signal system changes according to the amplitude of the reproduced luminance signal (according to the vertical correlation). The color signal system is the same as that shown in FIG.

It is easy to understand that the example shown in FIG. 2 also provides the same effects as the example shown in FIG.

It goes without saying that the present invention is not limited to the above-described embodiments, and that various other configurations may be adopted without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, the reproduced luminance signal and the reproduced chrominance signal are mixed in a state where they are separated in each band, and this mixed signal is passed through the delay line, so the delay line for two horizontal periods of the charge transfer type is used. A comb filter circuit that can separate both the luminance signal and the chrominance signal can be obtained, which has advantages such as a reduction in the number of elements, a reduction in cost, and a reduction in mounting space.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the comb filter circuit of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. 3 is a block diagram showing an example of a conventional comb filter circuit. be. 1Y is a reproduced luminance signal input terminal, 1C is a reproduced chrominance signal input terminal, 6Y is a luminance signal output terminal, 6C is a chrominance signal output terminal, 9 and 10 are one horizontal period delay lines each consisting of a CCD, and 11 and 13 are low, respectively. Bandpass filters 12 and 15 are bandpass filters, 14 and 17 are adder circuits, and 20 is a subtraction circuit.

Claims (1)

[Claims] 1. The crosstalk of the reproduced luminance signal is interleaved with the main signal by 1/2h (h is the horizontal frequency), and the crosstalk of the reproduced color signal is interleaved with the main signal by 1/4h. In a comb-shaped filter circuit that separates a luminance signal and a chrominance signal from a signal, a mixed signal obtained by mixing the reproduced luminance signal and the reproduced chrominance signal in a state where they are separated in frequency bands is mixed in two horizontal periods of charge transfer type. The luminance signal is supplied to the delay line, and the luminance signal is the above mixed signal and the above two charge transfer type signals.
Crosstalk components of the luminance signal are removed from the one-horizontal-period delayed signal extracted from the one-horizontal-period delay point of the horizontal-period delay line, and the luminance signal is separated through a low-pass filter, and the color signal is the above-mentioned mixed signal. and a two-horizontal period delayed signal obtained at the output side of the two-horizontal period delay line of the charge transfer type, and the crosstalk component of the color signal is removed and the color signal is separated through a bandpass filter. A comb filter circuit.