KR0183161B1 - Circuit for converting video signal of ntsc to that of pal - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

A color carrier conversion circuit of a video device.

2. The technical problem to be solved by the invention

The present invention relates to a circuit for converting NTSC color carriers into PAL color carriers by using an applied composite synchronization signal, so that NTSC video can be viewed on a PAL TV.

3. Summary of Solution to Invention

The carrier conversion circuit according to the present invention; First dispensing means for dispensing a carrier of the NTSC system and outputting a first dispensing carrier; Second dividing means for dividing a PAL carrier to output a second divided carrier, and phase shifting the second divided carrier to output phase shift signals; Horizontal synchronous signal separating means for separating a horizontal synchronous signal from an NTSC type synchronous signal using the first division carrier; Burst flag generating means for generating a burst flag from said separated horizontal synchronization signal using said second division carrier; Gate pulse generating means for dividing and inverting the burst flag to generate a divided burst flag and an inverted burst flag, respectively, and combining the generated burst flags to generate a plurality of gate pulses; And mixing means for matching each of the gate shift pulses to each of the phase shift signals and outputting the mixed signal as a PAL color carrier.

4. Important uses of the invention

Video tapes or laser discs recorded in NTSC format can be viewed on a PAL television.

Description

NTS / ARM color carrier conversion circuit

1 is a diagram showing the configuration of a conventional NTSC / PAL color video signal conversion circuit.

2 is a diagram showing the configuration of an NTSC / PAL color carrier conversion circuit according to the present invention.

3 is an operation waveform diagram of signals processed by a color carrier conversion circuit according to the configuration of FIG.

* Explanation of symbols for main parts of the drawings

200,210: Dispenser 220: Horizontal sync signal separator

230: waveform shaping unit 240: burst flag (BF) generating unit

250: burst flag adjusting unit 260: gate pulse generator

270 mixing portion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color carrier conversion circuit of a video device, and in particular, a color carrier of a NTC (National Television System Committee: NTSC) method, a color carrier of a Phase Alternative by Line (hereinafter, PAL) method. To a circuit for converting to.

Representative video devices that reproduce color video signals include color televisions, VTRs, and laser disc players (hereinafter referred to as LDPs). Since these video devices, especially LDP, are largely divided into NTSC, PAL, and combined methods, they can be appropriately selected according to the broadcasting method of each region. On the other hand, in the type and number of laser discs, the NTSC type laser discs dominate. However, in order to reproduce a color video signal recorded on an NTSC laser disk in a PAL television, it is required to convert the NTSC color video signal into a PAL color video signal.

1 is a diagram showing the configuration of a circuit for converting a conventional NTSC color video signal into a PAL color video signal. The color video signal converting circuit is manufactured and sold by Pioneer, Japan. The circuit used for the LDP of 1450.

Referring to FIG. 1, the phase shift 100 converts a color carrier 4fpsc into a carrier having a phase of -45 °, 0 °, and + 45 °, respectively, and uses an applied burst flag (BF). To output the PAL carrier Cp. The frequency of the color carrier (fpsc) is 4.43MHz, which is the carrier frequency of the PAL method, and the frequency of the color carrier (4fpsc) is 17.7MHz. In this case, the delayed horizontal synchronization signal Hsync may be applied to the phase shift 100 instead of the burst flag BF. The PAL carrier Cp output from the phase shift 100 is multiplied by the NTSC carrier fnsc (3.58 MHz) by the multiplier 102, and the multiplied carrier is the first low pass filter LPF1. Low pass filtering by 104. In this case, the filtered component is 854 KHz corresponding to the difference between the PAL carrier Cp and the NTSC carrier fnsc.

The multiplier 108 multiplies the output of the first low pass filter 104 and the output of the first band pass filter (BPF1) 106 which outputs only the NTSC system color carrier from the NTSC system color image signal Vi. The second band pass filter (BPF2) 110 outputs a color carrier of 4.43 MHz by band pass filtering the result output from the multiplier 108. The 4.43 MHz color carrier is amplified by the first amplifier (AMP1) 112 and then applied to the adder 118. Then, the adder 118 is low pass filtered by the second low pass filter (LPF2) 114 and then outputs through the 4.43 MHz trap circuit 116 to the NT signal Y signal Y n and the first amplifier 112. ), And the second amplifier AMP2 120 amplifies the added result and outputs the color image signal Vo. The color video signal Vo thus output is a video signal that can be reproduced by a PAL television. That is, the color video signal Vo is a video signal converted as a PAL video signal.

The processed NTSC / PAL conversion method is called a half color conversion method. In order to convert an image signal according to this method, a burst flag (BF) or a delayed horizontal synchronization signal (Hsync) must be applied. . Accordingly, there is a limitation that the conversion operation of the image signal is performed only when the system delays and applies the burst flag BF or the horizontal synchronization signal Hsync. In addition, when the horizontal synchronization signal (Hsync) is unstable or the horizontal synchronization signal (Hsync) is not correctly separated in the equalization pulse section, there is a problem that the image quality of the displayed image signal is degraded. In addition, the analog delay method, which is mostly used to delay the horizontal sync signal (Hsync), causes a complexity of the system and has a problem in that the gating of the burst section is not accurately gated. In addition to the above problems, in the PAL method, there is a problem in that a delayed burst flag (BF), which should be used when adjusting the gain of the burst and the color carrier, does not occur due to the difference in processing paths of the Y and C signals.

Accordingly, an object of the present invention is to provide a circuit for converting an NTSC color carrier to a PAL color carrier using a composite video signal.

Another object of the present invention is to provide an NTSC / PAL color carrier conversion circuit for improving the quality of the converted video signal.

It is still another object of the present invention to provide an NTSC / PAL color carrier conversion circuit that can be used for gain adjustment of burst and color carrier.

In accordance with the above objects, the present invention; First dispensing means for dispensing a carrier of the NTSC system and outputting a first dispensing carrier; Second dividing means for dividing a PAL carrier to output a second divided carrier, and phase shifting the second divided carrier to output phase shift signals; Horizontal synchronous signal separating means for separating a horizontal synchronous signal from an NTSC type synchronous signal using the first division carrier; Burst flag generating means for generating a burst flag from said separated horizontal synchronization signal using said second division carrier; Gate pulse generating means for dividing and inverting the burst flag to generate a divided burst flag and an inverted burst flag, respectively, and combining the generated burst flags to generate a plurality of gate pulses; And a mixing means for mixing each of the gate shift pulses with each of the phase shift signals and then outputting the mixed signal as a PAL color carrier.

In addition, a circuit according to the present invention for converting an NTSC color carrier to a PAL color carrier according to a half color conversion method; First dispensing means for dispensing 16SC and 32C NTSC carriers 4fsc and outputting them as a first frequency division carrier and a second frequency division carrier; A second frequency division carrier and a fourth frequency division carrier by dividing the PAL carrier 4fpsc into two and four divisions, respectively, and outputting first to third phase shift signals by phase shifting the fourth division carrier. Dispensing means; Horizontal synchronous signal separation means for separating the first horizontal synchronous signal (Hsync1) from the NTSC composite synchronous signal (Csync) using the first division carrier; Horizontal sync signal generating means for increasing the duty of the first horizontal sync signal using the second division carrier and outputting the first horizontal sync signal Hsync1 having increased duty as a second horizontal sync signal Hsync2. and; Burst flag generating means for generating a burst flag (BF1) from said second horizontal synchronizing signal (Hsync) using said third division carrier; The burst flag BF1 is divided into two, the burst flag BF1 and the two divided burst flags are inverted, the burst flag BF1, the two divided burst flags, the inverted burst flags, and the two are divided. Gate pulse generation means for generating first to third gate pulses GP1, GP2, and GP3 by combining the divided and inverted burst flags; And mixing means for matching each of the first to third gate shift signals to each of the first to third phase shift signals, and outputting them as a PAL color carrier Cpc.

A detailed description of a preferred embodiment of the present invention is shown in FIG. 2 showing a configuration of an NTSC / PAL color carrier conversion circuit according to the present invention, and a third showing an operation waveform of signals processed in the color carrier conversion circuit according to the configuration of FIG. It will be described with reference to the figure.

The first division unit 200 divides the carrier 4fnsc, which is four times the carrier of the NTSC system, into 16 divisions and 32 divisions, and outputs the first division carrier fnsc / 4 and the second division carrier fnsc / 8. do. At this time, the frequency of the carrier (4fnsc) is 14.318MHz. The second dispensing unit 210 divides the carrier (4fpsc) corresponding to four times the carrier of the PAL method into two and outputs the third dispensing carrier (2fpsc), and divides the carrier (4fpsn) into 4 -45 °. The first phase shift signal fsc1, the second phase shift signal fsc2 and the third shift signal fsc3 are also output by phase shifting by 0 ° and + 45 °. The waveforms of the signal 4fnsc input to the second divider 210 and the signals fsc1, fsc2 and fsc3 output from the second divider 210 are illustrated in FIG. 3A. As such, the second division unit 210 divides the carrier 4 fpsn into four divisions, and then shifts the phases by -45 °, 0 °, and + 45 ° so that the first phase shift signal fsc1 and the second phase shift signal fsc2 are performed. ) And the third shift signal fsc3 are based on a half color scheme.

The horizontal synchronous signal separator 220 separates the first horizontal synchronous signal Hsync1 from the composite synchronous signal Csync by using the first divided carrier fnsc / 4 output from the first divider 200. As described above, in the present invention, the first horizontal synchronization signal Hsync1 is generated from the composite synchronization signal Csync without using the horizontal synchronization signal or the burst flag applied separately from the system, and the burst flag BF to be described later is generated. In this case, the first horizontal synchronous signal Hsync1 is separated from the complex synchronous signal Csync. The first horizontal synchronous signal Hsync1 is a horizontal synchronous signal which is regularly separated from the equalization pulse and the vertical synchronous signal. FIG. 3B shows the first horizontal synchronization signal Hsync1 separated from the composite synchronization signal Csync.

The waveform shaping unit 230 shapes the waveform of the first horizontal synchronization signal Hsync1 by using the second division carrier fnsc / 8 output from the first division unit 200, and the first horizontal synchronization signal Hsync1. ) Is output as the corrected second horizontal synchronization signal Hsync2. FIG. 3 (c) shows that the duty cycle of the first horizontal synchronization signal Hsync1 is corrected in the waveform shaping unit 230. The reason for correcting the duty is to increase the stability of the synchronization signal and to improve the stability of the synchronization signal. For example, to be used for On Screen Display.

The burst flag (BF) generator 240 may set and re-set the signals at the time t1 and the time t2 based on the rising edges of the second horizontal synchronization signal Hsync2 as shown in FIG. The set signal is generated to generate the first burst flag BF1. At this time, the time from the rising edge of the second horizontal synchronization signal Hsync2 to the time point t1 is 4.5 ms, and the time from the rising edge of the second horizontal synchronization signal Hsync2 to the timing t2 is 7.89 ms. The BF adjuster 250 includes a delay unit for delaying the generated first burst flag BF1 and a logic sum gate, so that the second burst flag BF2 whose duty is increased compared to the first burst flag BF1 may be selected. Output In this case, the increased pulse width is determined by the delay according to the Y signal and the C signal path difference. The first burst flag BF1 is applied to the gate pulse generator 260 to be used for color carrier gating.

The gate pulse generator 260 inputs the first burst flag BF1, receives the first burst flag BF1, the two divided first burst flags BF1, and the two divided and inverted first burst flags BF1. BF1 and the inverted first burst flag BF1 are combined with each other to form a first gate pulse GP1, a second gate pulse GP2 and a third gate pulse GP3 as shown in FIG. Will occur). The reason why such a gate pulse generator 260 is required is that the first phase shift signal fsc1 and the second phase shift signal having a phase of -45 °, 0 °, and + 45 ° for the half-color color conversion. This is because gating of each phase shifted carrier is necessary to mix fsc2) and the third phase shift signal fsc3 to be compatible with the PAL format.

The mixing unit 270 combines the first gate pulse GP1 and the first phase shift signal fsc1, the second gate pulse GP2 and the second phase shift signal fsc2, and the third gate pulse. The color carrier Cpc as shown in FIG. 3 (f) is output by combining GP3 and the third phase shift signal fsc3. At this time, the output color carrier Cpc is a color carrier according to the PAL scheme so that phase shift is performed.

As described above, the horizontal synchronization signal and the burst flag are generated from the composite synchronization signal, and the generated burst flag is used to generate gate pulses for half-color conversion. The advantage is that the converted video signal can be displayed without degrading the image quality. In addition, there is an advantage that the delayed burst flag required for adjusting the burst and the color carrier may be generated due to the difference in the processing paths of the Y and C signals.

Claims (6)

A circuit for converting NTSC color carriers to PAL color carriers according to a half color conversion method, comprising: first distributing means for dispensing an NTSC carrier and outputting a first divided carrier; And a second division means for dividing a PAL carrier to output a second divided carrier, phase shifting the second divided carrier to output phase shift signals, and a composite of an NTSC system using the first divided carrier. Horizontal synchronous signal separation means for separating the horizontal synchronous signal from the synchronous signal, burst flag generating means for generating a burst flag from the separated horizontal synchronous signal using the second division carrier, and dividing and inverting the burst flag A burst burst flag and an inverted burst flag are respectively generated, and the generated burst flags are combined to generate a plurality of gate pulses. And a gate pulse generating means and mixing means for matching each of the phase shift signals with each of the gate pulses and then mixing the gate pulses and outputting the mixed signals as a PAL color carrier. The apparatus of claim 1, further comprising waveform shaping means for outputting the shaped horizontal synchronous signal to the burst flag generating means after shaping the waveform of the separated horizontal synchronous signal. And a burst flag is generated from a horizontal synchronous signal whose waveform is shaped by the waveform shaping means using a division carrier. 3. The carrier conversion circuit according to claim 2, further comprising burst flag adjusting means for outputting an increased burst flag by increasing the duty of the burst flag output from said burst generating means. In a circuit for converting NTSC color carriers to PAL color carriers according to the half-color conversion method, the NTSC carrier 4fsc is divided into 16 divisions and 32 divisions, respectively. The first and second division means for outputting the carrier and the second division carrier and the PAL carrier 4fpsc are divided into two and four divisions to output a third division carrier and a fourth division carrier, respectively, and the fourth division carrier is phased. Second division means for shifting and outputting first to third phase shift signals, and horizontal synchronization for separating the first horizontal synchronization signal Hsync1 from the composite synchronization signal Csync of NTSC method using the first division carrier. The signal separating means and the second frequency division carrier increase the duty of the first horizontal synchronization signal, and output the first horizontal synchronization signal Hsync1 having increased duty as a second horizontal synchronization signal Hsync2. Horizontal Sync Signal Generation However, the burst flag generating means for generating the burst flag BF1 from the second horizontal synchronization signal Hsync using the third division carrier, and the burst flag BF1 are divided into two, and the burst flag BF1 is divided. ) And the two-divided burst flag, and the first to third gate pulses are combined by combining the burst flag (BF1), the two-divided burst flag, the inverted burst flag, the two-divided and inverted burst flag. Gate pulse generating means for generating the fields GP1, GP2, GP3 and the first to third gate shift signals corresponding to the first to third phase shift signals, respectively, and then mixed. Carrier conversion circuit comprising a mixing means for outputting as). 5. The carrier conversion method as claimed in claim 4, further comprising burst flag adjusting means for increasing the duty of the burst flag BF1 output from the burst generating means and outputting the burst flag BF2 having increased duty. Circuit. 5. The method of claim 4, wherein the second division means outputs the third division carrier and the fourth division carrier, and shifts the fourth division carrier by 45 ° to perform the first phase shift signal fsc1, And a second phase shift signal (fsc2) and a third phase shift signal (fsc3).