JPH0446487A - Three-line median comb-line filter - Google Patents

Abstract

PURPOSE:To eliminate the number of parts by exchanging the order of an 1H delay element for a BPF and placing the 1H delay element after the BPF. CONSTITUTION:Signals around 3.58MHz pass through a composite video signal by a BPF 11. The signal which is not delayed, the one 1H delayed, and the one 2H delayed by 1H delay memories 13 and 14 are made in the signal passing through the BPF 11. A chroma signal is obtained as an average signal with the signal 1H delayed by the 1H delayed memory 13 and an output signal from the intermediate value selection circuit 17 by the calculation of inverters 15 and 16, an intermediate value selection circuit 17, and an addition circuit 18. A luminance signal is obtained by subtracting the chroma signal of the addition circuit 18 from 1H delayed composite video signal by an 1H delay memory 12. Thus, the number of BPF is reduced from 3 to 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an NTSC system that improves the separation performance of luminance signals and chroma signals in NTSC system composite video signal reproducing equipment such as NTSC system television receivers and VCRs.
This relates to a 3-line median bridge filter in the TSC system.

2. Description of the Related Art In recent years, there has been a demand for higher image quality in video signal reproducing equipment, including televisions. For this reason, NTSC video signal playback equipment has a Y/C separation circuit that is
Line comb filters have been replaced by three line median bridge filters which greatly reduce the occurrence of dot interference.

An example of the above-mentioned conventional NTSC type three-line median comb filter will be described below with reference to the drawings.

FIG. 2 shows a schematic block diagram of a conventional NTSC type three-line median comb filter. In FIG. 2, 21 and 22 are 1H delay memories that delay the signal by 1H period. 23 to 25 are band pass filters that take out the area around 3.58MI+2. 26 and 27 are inverters that invert the signals. 28 is an intermediate value selection circuit.

29 is an addition circuit. 30 is a condolence circuit.

The operation of the 3-line median comb filter in the NTSC system configured as described above will be described below.

The composite video signal is transmitted through 1H delay memory 21 and 1H delay memory 2.
2 produces an undelayed signal, a 1H delayed signal, and a 2H delayed signal.

The 3rd line signal is bandpass filtered 23.24.25
Therefore, signals around 3.5sMH2 pass through. This includes not only the chroma signal but also a high-frequency brightness signal, but the brightness signal is converted to
becomes 0 when passing through. Chroma signal is inverter 26
27, the intermediate value selection circuit 28, and the addition circuit 29, the signal is obtained as the average of the 1H delayed signal and the output signal from the intermediate value selection circuit 28. The luminance signal is 1
It is obtained by adding the chroma signal from the addition circuit 29 from the H-delayed composite video signal.

The Y/C separation of the chroma signal and luminance signal thus obtained is performed accurately, and cross color interference and dot interference are less likely to occur.

Problems to be Solved by the Invention However, since the above configuration requires a large number of parts, when high-density packaging is considered, it is required to reduce the number of parts or make each part smaller.

In view of the above-mentioned problems, the present invention aims to provide a 3-line median comb filter for the NTSC system that can be realized with a smaller number of parts than the conventional filter.

Means for Solving the Problems In order to solve the above problems, the 3-line median comb filter in the NTSC system of the present invention changes the order of the 1H delay element and the bandpass filter, and places the 1H delay element after the bandpass filter. It was placed there.

Effect of the Invention According to the above-described configuration, the present invention increases the number of bandpass filters by three instead of increasing the number of 1H delay elements from two to three.
By reducing the number of parts from one to one, the total number of parts is reduced to one compared to the previous model.
points can be reduced.

EXAMPLE Hereinafter, a three-line median bridge filter for the NTSC system according to an example of the present invention will be described with reference to the drawings. FIG. 1 shows 3 in the first embodiment of the present invention.
1 shows a schematic block diagram of a line median comb filter.

In Fig. 1, 11 is a band pass filter, 12 to 1
4 is a 1H delay memory that delays by 1H period, 15 and 16 are inverters that invert the signal, 17 is an intermediate value selection circuit,
18 is an addition circuit, and 19 is a condolence circuit.

The operation of the 3-line median bridge filter in the NTSC system configured as described above will be explained below with reference to FIG.

The composite video signal is passed through a bandpass filter 11 into 3.
58M) Signals around 12 pass through. The signal that has passed through the bandpass filter 11 is processed by a 1H delay memory 13 and a 1H delay memory 14 into an undelayed signal, a 1H delayed signal, and a 2H delayed signal. This includes not only the chroma signal but also a high-frequency brightness signal, but the high-frequency brightness signal passes through the adder circuit 18 by the computation of the inverters 15 and 16, the intermediate value selection circuit I7, and the adder circuit 18. When you do that, it becomes O. The chroma signal is obtained as the average signal of the signal delayed by 1H by the 1H delay memory 13 and the output signal from the intermediate value selection circuit 17 by the operations of the inverters 15 and 16, the intermediate value selection circuit 17, and the addition circuit 18. It will be done. The luminance signal is obtained by adding the chroma signal from the addition circuit 18 from the composite video signal delayed by 1H by the 1H delay memory 12.

The operation of the 3-line median bridge filter in the NTSC system configured as described above is exactly the same as the conventional 3-line median comb filter, but when comparing the number of parts with the conventional one, the number of parts is 1HHJ. 2 to 3
At the same time, the number of bandpass filters is reduced from three to one.

Effects of the Invention As described above, according to the present invention, a bandpass filter and a
By changing the order of the H delay elements, the total number of parts can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a 3-line median comb filter in the NTSC system according to the first embodiment of the present invention, and FIG. 2 is a schematic block diagram showing a conventional example of a 3-line median comb filter in the NTSC system. . 11...Band pass filter, 12-14...
...1HJ memory 5 to 16...Inverter, 17...--Intermediate value selection circuit, 18...
...Addition circuit, 19...1 summer circuit.

Claims (1)

[Claims] a bandpass filter that receives an NTSC composite video signal; a first 1H delay element that delays the NTSC composite video signal by 1H period; and a first inversion element that inverts the output from the bandpass filter; a second 1H delaying the output from the bandpass filter for a period of 1H;
a delay element; a third 1H delay element that further delays the output from the second 1H delay element; a second inversion element that inverts the output from the third 1H delay element; Comparing the magnitudes of the outputs of the three lines of the first inverting element, the second 1H delay element, and the second inverting element,
an intermediate value selection circuit that selects a line with a middle size when the lines have different sizes, and selects one of the two lines of the same size if two of the three lines have the same size; an addition circuit that adds the outputs of two 1H delay elements and the intermediate value selection circuit and divides the result by 2; and a subtraction circuit that subtracts the output value of the addition circuit from the output value of the first 1H delay element. 3-line median comb filter with circuit.