JPS6367997A - Time base correcting device - Google Patents

Abstract

PURPOSE:To correct a time base fluctuation by providing a line memory for recording a luminance signal and a line memory for recording a chroma signal, processing the writing and the reading of the two line memories in a difference timing, synchronously outputting with a constant clock for respective signals, mixing again and outputting them. CONSTITUTION:A reproduced video signal is separated into the luminance signal and the chroma signal by a Y/C separating circuit 1 and these signals are inputted to processing systems 2a, 2b for processing the respective signals. In a controller 3, a writing pulse synchronizing with a horizontal synchronizing signal is outputted to the processing system 2a of the luminance signal 2a and the luminance signal digitally converted synchronously with this pulse is written. The writing is carried out in the timing synchronizing with both the horizontal synchronizing signal and a color burst. The contents written in the line memories 5a, 5b are read in respectively different constant timing, thereby, analog converted, inputted to a mixer 7 from which a video signal is outputted.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a device for correcting shaking, bending, etc. on a screen that occurs during playback of a video tape recorder (VTR), and is applicable to all devices that handle video signals. Used in many electronic devices.

(Prior Art) In a device such as a VTR that uses a tape head system as an FM signal transmission path, the reproduced signal fluctuates in the time direction due to mechanical factors, which appears as "shaking" or bending in the screen. Conventionally, in order to prevent this type of fluctuation, time base correction processing has been performed to correct the luminance signal and chroma signal together based on the burst of the video signal.

(Problems to be Solved by the Invention) However, like the video playback signal, the luminance signal is FM modulated and the chroma signal is low frequency converted and recorded, so the playback signal is not a complete NTSC signal but an interleaved signal.
The ping relationship is broken.

For this reason, if the luminance signal and the chroma signal were subjected to time axis correction processing at the same time as in the past, it would not work accurately as a time axis correction device.

(Means for Solving the Problems) The present invention corrects time axis fluctuations that occur during reproduction of a video signal, and separates the reproduced video signal into a luminance signal and a chroma signal, and separates the reproduced video signal into a luminance signal and a chroma signal. The processing system includes a luminance signal processing system and a chroma signal processing system, each of which includes means for converting into a digital signal, a line memory,
These processing systems perform processing at different timings.

(Function) It is equipped with a line memory for recording luminance signals and a line memory for recording chroma signals, and writing and reading of these two line memories are processed at different timings,
Each signal is output synchronously with a fixed clock, mixed again, and output.

By changing the processing timing for these line memories, time axis fluctuations are corrected.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The drawing shows a processing circuit applied as a time axis correction device according to the present invention.

The reproduced video signal is separated into a luminance signal and a chroma signal by a Y/C separation circuit 1, and these signals are input to processing systems 2a and 2b that process the respective signals.

Further, a color burst is extracted from this Y/C separation circuit 1 and inputted to the controller 1-roller 3. Similarly, a horizontal synchronizing signal is separated from the luminance signal and is manually input to the controller 1-roller 3. The luminance signal processing system 2a and the chroma signal processing system 2b are A/D converters 4a and 4, respectively.
b1 line memories 5a, 5b, D/A converter 6a,
6b. Line memory 5a, 5b
uses an integrated circuit that can perform reading and writing asynchronously using separate clocks. The controller 1-roller 3 outputs a write pulse synchronized with the horizontal synchronizing signal to the luminance signal processing system 2a, and writes the digitally converted luminance signal in synchronization with this pulse. On the other hand, data is written into the line memory 5b of the chroma signal processing system 2b at a timing synchronized with both the horizontal synchronization signal and the color burst. Then, the contents written in the line memories 5a and 5b are simultaneously read out at different fixed timings (for example, four times the color subcarrier), converted into analog signals, and inputted to the mixer 7, from which a video signal is output. In this way, by changing the clock timings for writing and reading from the line memories 5a and 5b, the time axis fluctuations occurring in these two signal systems can be corrected.

(Effects of the Invention) As described above, according to the present invention, it is possible to correct temporal fluctuations in a video signal using a line memory.

[Brief explanation of the drawing]

The drawing is a block diagram showing an embodiment of a time axis correction device according to the present invention. 1... Y/C separation circuit 2a... Luminance signal processing system 2b... Chroma signal processing system 3... Controllers 5a, 5b... Line memory

Claims (1)

[Claims] 1) A luminance signal processing system and a chroma signal processing system that correct time axis fluctuations that occur during video signal reproduction, and that separate the reproduced video signal into a luminance signal and chroma signal and process each signal separately. 1. A time axis correction device comprising: a processing system comprising means for converting into a digital signal, a line memory, and a means for converting into an analog signal, each processing system processing at different timings.