JPS6031377A - System converting device of video signal - Google Patents

Abstract

PURPOSE:To prevent the flicker of a reproduced picture by suppressing the increase in luminance generated at a video signal portion obtained through the image pickup of a video camera having a different field frequency for the reproduced picture by means of a system converting synchronizing signal. CONSTITUTION:In image picking up the reproducing picture of the HDVS system by the video camera 3 of the PAL system and in conducting the system convertion for the video signal, the signal reproducing device 1 of the HDVS system is synchronized by the system converting synchronizing signal having a frequency being 1/5 of the field frequency of the video signal obtained from the camera 3 so as to synchronize the signal to the synchronizing signal of the HDVS system. Thus, the luminance of the determined field of the video signal of the PAL system is increased and the signal level of the video signal converted into the PAL system is made constant by applying AM modulation only to said field based on said synchronizing signal in an AM modulation circuit 5 so as to prevent the flicker of the reproduced picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal system for converting a high-definition video system (hereinafter referred to as HDVS) video signal having a different field frequency into a PAL video signal, for example. This invention relates to a conversion device.

[Background technology and its problems]

For example, in order to perform offline editing of an HDVS video signal, it is necessary to convert it to, for example, an NTSC or PAL video signal. The simplest way to perform this format conversion is to play the HDVS format video signal on a monitor,
This reproduced image is captured by, for example, a PAL video camera and converted into a PAL video signal, for example. However, when a reproduced image is captured by a video camera and an HDVS video signal is converted into a PAL video signal, flicker occurs in the reproduced image of the PAL video signal obtained by the conversion. This flicker occurs because the field frequencies are different, 60 Hz for the HDVS system and 0 Hz for the PALPAL system.

That is, the photocathode of a PAL video camera, for example, is exposed by a UHDVSHDVS system image,
An electron beam scans this exposed photocathode to extract a video signal, but one field in the PAL system is π.
During the field, the electron beam scanning the optical ridge surface has a time delay of i seconds with respect to the electron beam scanning the cathode ray tube of the monitor that reproduces the HDVS video signal. occurs. Therefore, after 5 fields of a PAL video camera, the delay time becomes small, and becomes a delay time of 1 (corresponding to 1 field of a DVS system). The electron beam scanning the monitor's cathode ray tube will be overtaken by the electron beam scanning the monitor's cathode ray tube.Therefore, in the 6th field F of a PAL-based high-speed camera, the photocathode that has already been exposed will be exposed once more. If the photocathode exposed twice in this way is scanned by the photocathode to extract the video signal, the brightness of the video signal increases and flicker occurs every 5 fields.

The frequency of flicker occurrence, that is, the flicker frequency, is once every 5 fields, and the field frequency of the PAL system is 5.
Since it is 0 Hz, it is l'QHz, and corresponds to 1QHz, which is the greatest common divisor of the field frequencies of 60Hz and 50Hz in the HDVS system and PAL system.

FIG. 1 schematically explains how the flicker occurs. In FIG. 1, A indicates a video signal captured by a PAL video camera, and B
indicates an HDVS format video signal. As is clear from FIG. 1, in the PAL video camera, the 6th and 7th fields of the HDVS video signal are captured in the 6th field, with a period of - seconds, or 0 to 1QHz. This causes flicker to occur at this frequency.

In this way, in the past, for example, the reproduced image of an I (DVS system) video signal was
When converting a video signal by taking an image with a PAL video camera, there is a drawback that flicker occurs in the reproduced image of the PAL video signal obtained by conversion.

[Purpose of the invention]

Therefore, the present invention has been proposed in view of the above-mentioned circumstances. 1. A video signal obtained by capturing a reproduced image of, for example, an HDVS video signal with a video camera of, for example, PAL system, having a different field frequency. It is an object of the present invention to provide a video signal format conversion device that suppresses a partially occurring increase in brightness and prevents flickering of a reproduced image of the video signal.

[Summary of the invention]

In order to achieve this purpose, a video camera according to the present invention has a field frequency of 50 Hz, and a synchronization signal for format conversion in the @55 field period is generated based on the vertical synchronization signal of the video signal of this video camera. This system conversion synchronization signal is used to synchronize the reproduced video signal of the monitor, and the video signal from the video camera is AM modulated based on the system conversion synchronization signal to lower the signal level. It is characterized by keeping the video signal level constant.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 is a block diagram of a video signal format conversion device according to the present invention. FIG. 2 shows a video signal format conversion device that converts, for example, a high-definition video system (hereinafter referred to as DVS) video signal to, for example, a PAL format video signal.

As mentioned above, if you try to convert the format of the video signal by capturing a reproduced image of an HDVS video signal using a PAL video camera, for example, the resulting PAL video signal will be Flicker occurred in the reproduced image at a cycle of 1 second. This means that the HDVS field frequency is 60.
This is due to the fact that the field frequency of the PAL system is as low as 50I (Hz) compared to that of Hz.

In Fig. 2, for example, the time base correction circuit ('IBC)
An HDVS video signal reproduced by a signal reproducing device 1 such as a video tape recorder equipped with a video tape recorder is sent to a monitor 2, and a reproduced image is displayed on the monitor 2. The reproduced image displayed on the cathode ray tube of the monitor 2 is captured by, for example, a PAL video camera 3. A PAL video signal captured by the video camera 3 is sent to a synchronization signal generation circuit 4. FIG. 3 shows a block diagram of this synchronizing signal generating circuit 4. As shown in FIG.

The PAL video signal inputted from the input terminal 11 of the synchronization signal generation circuit 4 is separated into a vertical synchronization signal A in FIG.
At step 3, this vertical synchronizing signal is frequency-divided by one to produce a synchronizing signal for format conversion with a five-field period as shown in FIG. 4B. The period of this synchronization signal for format conversion is equal to the period of every 6 fields of the video signal of the HDVS format, and the PLL circuit 14f has a voltage controlled oscillator with an oscillation frequency of 60 Hz, which is equal to the field frequency of the HDVS format: Synchronization signal for format conversion By locking, the H shown in FIG.
A vertical synchronization signal for a DVS video signal is created. This vertical synchronization signal generated by the PLL circuit 14 is sent to the signal reproducing device 1, so that the signal reproducing device 1
For example, the drum servo circuit and time axis correction circuit of a video tape recorder receive synchronization. As a result, the HDVS video signal reproduced by the signal reproducing device I is synchronized with the synchronization signal for format conversion, and the PAL video signal obtained by the video camera 3 is set in a fixed field. The brightness will only increase. on the other hand,
In the synchronization signal generation circuit 4, the monostable multi-by-break monomulti 15, which is triggered by the synchronization signal for system conversion, generates a pulse width for one field corresponding to the field in which the brightness of the video signal of the PAL system has increased. A pulse signal shown in the fourth diagram is generated. Note that instead of using the monomulti 15, the pulse signal is generated using a frisible flop that is sent by the synchronization signal for format conversion and reset by the vertical synchronization signal inputted to the -frequency divider circuit 13. It's okay. By the way, the pulse signal generated by the monomulti 15 is sent to the AM modulation circuit 5 into which the PAI video signal of the video camera 3 is input, so that the PAL video signal is AM modulation is performed in @AM modulation circuit 5 based on the pulse signal. That is, the video signal of the field portion where the brightness has increased is attenuated by, for example, an attenuator forming the AM modulation circuit 5 until it reaches the same level as the video signal of the other fields. As a result, HDV
The signal level of the PAL video signal obtained by capturing the reproduced image of the S format video signal with the video camera 3 becomes constant and is output from the output terminal 6 of the AM modulation circuit 5, and the PAL video signal is converted into the PAL format. Flicker in the reproduced image of the converted video signal is prevented.

According to the present invention, the field frequency is 5QI.
- (z, for example, I
When the video camera 3 of the L format takes an image and converts the format of the video signal, the P obtained from the video camera 3 is
A signal reproducing device 1 that reproduces an HDVS system video signal is synchronized by a system conversion synchronization signal having a field frequency of 1 for an AL system video signal, and the HDVS system video signal is synchronized with the synchronization signal. . As a result, the above P
The AM modulation circuit 5 performs AM modulation on only the field based on the synchronization signal, so that the brightness of only the fixed field of the AL format video signal increases, thereby converting the video format to the PAL format. The signal level of the signal becomes constant, and flickering of the reproduced image of the video signal obtained by format conversion is prevented.

Incidentally, in the above embodiment, an example was described in which a video signal of the HDVS format is converted into a video signal of the PAL format, but the present invention is also applicable to cases where, for example, a video signal of the NTSC format is converted to a video signal of the PAL format. Ru.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a video signal of, for example, I (DVS system) with a field frequency of 5QHz is displayed on a monitor, and this reproduced image is displayed as a video signal of, for example, PAL system with a field frequency of 50 Hz. The video signal of the HDVS system is synchronized using a synchronization signal for format conversion, which is obtained by dividing the vertical synchronization signal of the PAL video signal obtained by capturing an image with a video camera by one, and By performing AM modulation on the field portion where the brightness of the PAL video signal has increased, the signal level of the video signal converted to the PAL format is kept constant.
Flicker in the reproduced image of the video signal converted to the AL system is prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically explaining the cause of flicker that occurs when a video signal of the HDVS format is converted to, for example, a PAL format video signal, and FIG. 2 is a block diagram of a video signal format conversion device according to the present invention. FIG. 3 is a block diagram of the synchronizing signal generating circuit of the system converter, and FIG. 4 is a waveform diagram for explaining the operation of the synchronizing signal generating circuit. 1...Signal reproducing device 3...Video camera 4...Sync signal generation circuit 5...AM modulation circuit 6...Output terminal 12...Vertical synchronization signal separation circuit 13...-Frequency division Circuit 14... PLL circuit 15... Monostable multi-vibration patent applicant Sony Corporation representative Patent attorney Kodo Koike 1) Sakae Mura -

Claims (1)

[Claims] A video signal with a field frequency of 5QHz is reproduced on a monitor, and this reproduced image is reproduced with a field frequency of 50H.
Z video camera captures an image, extracts a 5-field period synchronization signal for format conversion based on the vertical period signal of the video signal of this video camera, and synchronizes the reproduced video signal of the monitor using this synchronization signal for format conversion. A video signal method characterized in that the video signal level is made constant by lowering the signal level of the video signal from the video camera based on the synchronization signal for format conversion.