JPH04185194A - Delay element - Google Patents

Abstract

PURPOSE:To obtain a delay element for both the PAL/NTSC system by providing a selector selecting either an output signal from a 1st delay section or an output signal from a 2nd delay section to be outputted to an external device depending on a switching signal sent from a switching signal generating section to the delay element. CONSTITUTION:A switching signal generating section 16 discriminates whether a video signal is an NTSC signal or a PAL signal depending on a period of a clock signal inputted to a delay memory to generate the NTSC and PAL switching signal. Then a selector 17 selects an output of a delay section 14 when the video signal is the NTSC signal depending on the switching signal from the switching signal generating section 16 and selects the output side of a delay section 15 when the video signal is a PAL signal and the selected signal is outputted to the outside of the memory. Thus, the delay element is provided with the delay sections 14,15, the switching signal generating section 16 and the selector 17 to attain delay for a comb-line filter for both the PAL/ NTSC signals. Thus, the delay element for both the PAL/NTSC system is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a delay element of a comb filter that is often used for Y/C separation in composite video signal reproducing equipment such as television receivers.

BACKGROUND OF THE INVENTION In recent years, there has been a demand for higher picture quality in domestic video signal reproducing equipment, including televisions, and comb filters have become mainstream in the Y/C separation circuits of NTSC video signal reproducing equipment. The same trend is also seen in Europe, where video signal playback equipment, including televisions, is required to have higher image quality, and PAL video signal playback equipment is becoming more and more popular.
In the C separation circuit, the conventional bandpass filter and notch filter have been replaced by comb filters that reduce cross color.

On the other hand, each television manufacturer is
They have been made separately for TSC (domestic use) and PAL (for Europe), but since designing for both can be expected to reduce costs due to mass production effects, we are looking for something that can be used for both NTSC and PAL systems. This concept is the same for comb-shaped filters and delay elements used in comb-shaped filters, and there is a demand for products that can be used not only in Japan but also in Europe.

An example of a delay element used in the above-mentioned conventional domestic comb filter will be described below with reference to the drawings.

FIG. 2 shows a schematic block diagram of a delay memory used in a conventional domestic comb filter. 21 indicated by a broken line in FIG. 2 is a memory main body. 22 is an input clock pin. 23 is a delay cell that delays the signal for one clock period by the input pin 22. Memory 21 is NT
It has 910 delay cells 23 corresponding to one horizontal period (1H) of the SC method.

The operation of the delay memory configured above will be described below.

The input clock bin 22 is an NTSC sampling system.
A clock of 14.31818 MHz corresponding to the clock is input. Each of the 910 delay cells 23 receives a tarlock signal from the input clock pin 22, delays the signal input from the previous delay cell by one clock, and sends it to the subsequent delay cell. That is, the delay cell 23b is the delay cell 23a.
The signal from the cell is delayed by one clock and sent to the delay cell 23c.

Delay cell 23c further delays the signal delayed by delay cell 23b by one clock and sends it to delay cell 23d.

The signal input to the memory 21 in this way is NTSC.
The signal is output after being delayed by 910 clocks corresponding to one horizontal period (1H) of the system.

Problems to be Solved by the Invention However, the above configuration can only support the NTSC system and cannot support the PAL system. This is because a PAL type comb filter requires a delay of 2270 sampling clocks corresponding to 2H period.

In view of the above-mentioned problems, the present invention provides not only NTSC signals but also
PAL, which also supports PAL signals, /NTSCNTSC
It is related to the formula.

Means for Solving the Problems In order to solve the above problems, the delay element of the present invention has an NTS
a first delay unit capable of delaying by 1H period of the C method;
The signal delayed by the delay unit is further delayed and the first signal is
a second delay section that can delay the 2H period of the PAL system when combined with the delay section; a clock signal input bin that inputs an external clock signal; and a second delay section that can delay the period of the clock signal sent from the clock signal input pin. a switching signal generation unit that generates a switching signal depending on the magnitude; and a switching signal generation unit that outputs either the output signal from the first delay unit or the output signal from the second delay unit to the outside according to the switching signal sent from the switching signal generation unit. It is equipped with a selector to send out.

According to the above-described configuration, the delay element delays the human input signal by the first delay section for a 1H period in the case of the NTSC system, and delays the human input signal by the first delay section and the second delay section for the 2H period in the case of the PAL system. It can be delayed.

Embodiment Hereinafter, a PAL/'NTSC NTSC system device according to an embodiment of the present invention will be explained with reference to the drawings. 1st
The figure shows a schematic block diagram of a delay memory in a first embodiment of the present invention.

In FIG. 1, numeral 11 indicated by a broken line is a memory main body. 12 is an input clock pin. 13 is input pin 1
This is a delay cell that delays one clock by the sampling clock from 2. 14 is 910 delay cells 1
This is a delay section having a delay of 3.

This allows the composite video signal to be delayed by the NTSC 1H period when the NTSC sampling clock signal is input from the input pin 12. 15 is 1360 delay cells 1
This is a delay section having a delay of 3.

The combined delay time of delay section 14 and delay section 15 is 2270
Become a clock. This means that when the PAL sampling clock signal is input from the input pin 12, the delay section 14
and the delay unit 15, the input composite video signal is
It can be delayed by 2H period of L. 16 is a switching signal generation section. Reference numeral 17 indicates an output signal from the delay section 14 or a delay section 15 based on the signal output from the switching signal generation section 16.
This is a selector that sends either of the output signals from the

The operation of the PAL/NTSC dual-purpose delay memory configured as described above will be explained below with reference to FIG.

The input clock pin 12 receives an NTSC or PAL sampling clock. The sampling clock for NTSC is 14.31818 MHz and the sampling clock for PAL is approximately 17.7 MHz. A delay unit 14 having 910 delay cells 13 and a delay unit 15 having 1360 delay cells 13 each have an input clock bin 1.
Upon receiving two clock signals, the signal inputted from the previous delay cell is delayed by one clock and sent to the subsequent delay cell. The composite video signal thus input to the delay memory 11 is
When the composite video signal is NTSC, the delay unit 14 delays it by exactly 1H period of NTSC.

Further, when the composite video signal input to the delay memory 11 is PAL, the composite video signal input to the delay memory 11 is processed by the delay units 14 and 15 to exactly P.
It is delayed by 2H period of AL. Is the video signal NTSC or P?
The determination of AL can be distinguished by the period of the clock signal from the input clock pin 12. The switching signal generation unit 16 determines whether the video signal is NTSC or PAL by looking at the cycle of the clock signal input to the delay memory, and generates a switching signal between NTSC and PAL. The selector 17 changes the video signal to NTS by the switching signal from the switching signal generating section 16.
In the case of C, select the output side of the delay section 14, and the video signal is PAL.
In this case, the output side of the delay section 15 is selected and outputted to the outside of the memory.

As described above, according to this embodiment, the delay units 14 and 15, the switching signal generation unit 16. By providing the selector 17, it is possible to provide a delay for the comb filter for both PAL/NTSC.

Effects of the Invention As described above, according to the present invention, there is a first delay section that can delay the 1H period of the NTSC system, and a signal delayed by the first delay section is further delayed to match with the first delay section. and a second delay unit that can delay the 2H period of the PAL system, a clock signal input pin that manually inputs a clock signal from the outside, and a switching signal that generates a switching signal depending on the period of the clock signal sent from the clock signal input bin. By providing a switching signal generation section that generates a switching signal, and a selector that outputs either the output signal from the first delay section or the output signal from the second delay section to the outside according to the switching signal sent from the switching signal generation section. , PAL/NTSC
Delays for dual-purpose comb filters can be implemented.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a delay memory according to a first embodiment of the present invention, and FIG. 2 is a schematic block diagram of a conventional delay memory. 11.21...Memory body, 12.22・Old・
- Input clock bin, 13.23...delay cell, 14°15...delay section, 16...switching signal generation section, 17...selector.

Claims (1)

[Claims] A first system capable of delaying a composite video signal by 1H period of the NTSC system.
a second delay section that further delays the signal delayed by the first delay section and can delay the signal by 2H period of the PAL system when combined with the first delay section; and a clock signal from the outside. a clock signal input pin that inputs a clock signal; a switching signal generation section that generates a switching signal according to the period size of the clock signal sent from the clock signal input pin; A delay element comprising a selector that outputs either the output signal from the delay section or the output signal from the second delay section to the outside.