KR920009643B1 - Assimilating signal recording and reproducing circuit - Google Patents

Abstract

The detected synchronous signal is recorded or reproduced from a cassette tape as single carrier using phase modulation. The recording circuit includes a rectifier (5) for obtaining absolute value of detected synchronous signal, a low pass filter (5) for limiting band of the synchronous signal, a look-up table (20) for generating signal to select phase shifters (10-13) according to the synchronous signal, and a brightness and a color signal processor (16,17). The reproducing circuit includes a resonator (32) for resonating reference signal for synchronous signal, a phase synchronizing loop (35) for locking phase by receiving output signal of the resonator and an oscillator (36), a phase detector (33) for detecting phase, and a second low pass filter (34) for filtering output signal of the phase detector to remove phase error.

Description

Video signal recording and reproducing circuit

1 is a recording frequency spectrum diagram of a conventional video cassette recorder.

2 is a recording block diagram of a video cassette recorder according to the present invention.

3 is a reproduction block diagram of a video cassette recorder according to the present invention;

4 is a recording frequency spectrum diagram of a video cassette recorder according to the present invention.

5 is a concrete circuit diagram of the phase detector 33 of FIG.

6 is an output waveform diagram of the video signal demodulator 42 of FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording and reproducing circuit of a moving picture signal in a video cassette recorder (hereinafter referred to as a VCR), and more particularly to a circuit for recording and reproducing a moving picture signal to a tape by a single carrier by phase modulation.

In general, a VCR records video information on a tape with a frequency spectrum as shown in FIG. Reference numeral 1 in FIG. 1 denotes a color subcarrier fc and color signal frequency domain low-converted to 629 KHZ, 2 denotes a luminance signal FM carrier, and 3 and 4 denote sidebands which are upper and lower sidebands of the luminance signal. As described above, in the conventional VCR recording and reproducing method, since the color signal is amplitude-modulated by low frequency conversion, the frequency of the color signal is changed so that the signal / noise ratio of phase modulation and amplitude modulation becomes worse when demodulating the color signal. There was a problem that caused an error.

It is therefore an object of the present invention to provide a circuit that detects moving signals and records and reproduces them on a tape as a single carrier by phase modulation.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of a video signal recording according to the present invention. An analog / digital converter 1 for inputting an analog composite video signal and converting it into a digital composite video signal, and an output digital video signal from the analog / digital converter 1, respectively. A frame memory 2 for delaying and outputting one frame by inputting the signal, a digital video signal of the analog-to-digital converter 1 and a delayed signal of one frame, which is an output of the frame memory 2, An adder 3 for comparing the signals and detecting the moving signals, a rectifier 4 for taking the moving signals detected from the adder 3 as absolute values, and filtering the signals taking the absolute values from the rectifier 4; A low pass filter 5 for limiting the band, an oscillator 8 for generating a predetermined oscillation frequency, and a divider 9 for dividing the frequency generated by the oscillator 8 A first to fourth phase shifters 10-13 for shifting different phases by respectively inputting the divided signals of the divider 9 and a band limited signal from the low pass filter 5 A lock up table (LUT) 20 for outputting a selection signal of the phase shifters 10-13, a synchronization separator 6 for separating synchronization by inputting a composite video signal, and the synchronization A mono multivibrator 7 for inputting a synchronously separated signal of the separating unit 6 to adjust the duty, and one of the phase shifters 10-13 is selected by an output signal of the LUT 20 and the A switch 14 for switching output in the synchronization signal blocking period in which the duty of the mono multi vibrator 70 is adjusted, and a Y / C separation unit for separating the luminance signal Y and the color signal C from the composite video signal ( 15) and a luminance signal destination for FM-modulating the luminance signal Y, which is an output of the Y / C separation unit 15, and outputting the signal. And a color signal processor 17 for modulating and outputting the low frequency conversion color signal C output from the Y / C separator 15, the luminance signal processor 16 and the color signal processor 17. A mixer 18 for mixing the output signal and the switch 14 switching selected signal to output a composite video signal, and a preamplifier 19 for amplifying and outputting the composite video signal output from the mixer 18. do.

3 is a reproduction block diagram of a video signal according to the present invention. The preamplifier 21 inputs and amplifies and outputs the video signal picked up from the head HD1, and the video signal amplified and output from the preamplifier 21. A first low pass filter 22 for inputting and filtering only the low-pass color signal, and a first band pass filter 33 for inputting and filtering only the high-pass luminance signal by inputting the video signal amplified and output from the preamplifier 21; Inputting the video signal amplified and output from the preamplifier 21 to filter and output only the carrier of the moving image signal, and demodulating and outputting the filtered low-pass color signal C of the low pass filter 22. The color signal processor 25, the luminance signal processor 26 for FM demodulating and outputting the filtered luminance signal Y of the first band pass filter 23, the color signal processor 25 and the luminance. Mix the output of the signal processor 26 In the mixer 27 for outputting the sum video signal, the synchronization separator 28 for separating the synchronization by inputting the FM demodulated signal output from the luminance signal processor 26, and the second band pass filter 24, A gain is obtained by adjusting the filtered moving picture carry signal to maintain a constant level. An auto gain controller (hereinafter referred to as AGC) 29 and a separate sync signal of the sync separator 28 are input to provide a duty. In order to detect the reference signal of the moving picture carrier by allowing the output signal of the AGC 29 to pass during the blacking period of the mono multi vibrator 30 to be adjusted and the synchronization signal of which the duty value is adjusted in the mono multi vibrator 30. A reference signal detector 31, a resonator 32 for resonating the reference signal of the moving picture carrier detected by the reference signal detector 31, an oscillator 36 for generating a reference frequency, and the resonator 32 The resonant signal of the oscillator 36 A phase synchronous loop circuit 35 for inputting a true signal to lock the phase, a phase detector 33 for detecting a phase by inputting an output signal of the automatic gain controller 29 and an output signal of the oscillator 36; And a second low pass filter 34 for filtering the phase detected signal of the phase detector 33 to remove an error component.

One embodiment of the present invention in the above configuration will be described with reference to FIGS.

First, referring to the recording block diagram of FIG. 2, the analog / digital converter 1 for inputting the analog composite video signal input through the input terminal P1 converts and outputs the digital composite video signal.

The frame memory 2 for inputting the composite video signal digitally converted by the analog / digital converter 1 outputs one frame delay. The adder 3 which inputs the signal converted into the digital composite video signal from the analog / digital converter 1 and the digitalized composite video signal delayed by one frame in the frame memory 2 compares the two signals to provide a moving picture signal. Detect. The rectifier 4 which inputs the moving picture signal detected by the adder 3 takes an absolute value and outputs it.

The low pass filter 5 which inputs the moving picture signal which takes the absolute value of the rectifier 4 filters and outputs and limits a band. The LUT 20 inputting the band-limited signal from the low pass filter 5 is 0 to 00000000-00001111, 1 to 00010000-00011111, 2 to 00100000-00111111, 3 to 01000000-11111111, and the phase is determined according to the level. The select signal of the mobile unit 10-13 is output. In addition, the divider 9 for inputting the oscillation frequency generated by the oscillator 8 outputs a predetermined divider. The signals divided by the divider 9 are applied to the phase shifters 10-13, respectively, to shift output different phases. The sync separator 6 for inputting the composite video signal input through the input terminal P1 separates and outputs the sync. The monovibration vibrator 7 which inputs the synchronization signal separated by the synchronization separation section 6 adjusts the duty value of the synchronization signal and outputs it. In this case, the switch 14 selects a phase shifted signal of the phase shifter 10-13 according to the output signal of the LUT 20 in the blanking period of the synchronization signal whose duty value is adjusted in the mono multi vibrator 7. Switch.

Meanwhile, the Y / C separator 15 for inputting the composite video signal input through the input terminal P1 separately outputs the luminance signal Y and the color signal C. The luminance signal processor 16 for inputting the separated luminance signal of the Y / C separator 15 outputs the FM modulated signal. The color signal processor 17 for inputting the low frequency converted color signal by the Y / C separator 15 modulates and outputs the color signal. The mixer 18 which inputs the output signal of the luminance signal processor 16 and the color signal processor 17 and the switched selected signal of the switch 14 mixes and outputs a composite video signal. The preamplifier 19 for inputting the composite video signal, which is the output of the mixer 18, is amplified by a predetermined signal to the head for recording.

4 is a recording frequency spectrum diagram according to the present invention. Referring to FIG. 4, the reproduction block diagram of FIG. 3 is explained. The preamplifier 21 for inputting the video signal picked up from the head HD1 outputs a predetermined amplification. . The low pass filter 22, which inputs the amplified output composite video signal of the preamplifier 21, filters and outputs a color signal as shown in FIG. The color signal processor 25 for inputting the filtered color signal of the low pass filter 22 demodulates the output. The first band pass filter 23 inputs the amplified output video signal of the preamplifier 21 to filter and output a high pass signal. The luminance signal processor 26 for inputting the filtered luminance signal Y of the first band pass filter 23 outputs the FM demodulated. The mixer 27 which inputs the output signals of the luminance signal processor 26 and the color signal processor 25 mixes the two signals and outputs a composite video signal. The second band pass filter 24, which inputs the amplified composite video signal of the preamplifier 21, filters and passes only the carrier of the moving signal.

The AGC 29, which inputs the filtered moving carrier signal of the second band pass filter 24, adjusts and outputs a gain to maintain a constant level. The luminance signal processing section 26 inputs the FM demodulated luminance signal, and the synchronization separation section 28 separates and outputs the synchronization. The mono multivibrator 30 for inputting the separated synchronization signal of the synchronization separator 28 adjusts the duty value of the synchronization signal and outputs it. The reference signal detector 31 which inputs the gain-controlled signal of the AGC 29 allows the gain-adjusted signal to pass through a blanking period of the synchronization signal whose duty value is adjusted in the mono multivibrator 30, thereby moving the moving picture carrier. Detect the reference signal. The resonator 32 that inputs the detected reference signal of the reference signal detector 31 resonates and outputs the resonance signal. The phase-locked loop circuit 35 for inputting the resonance signal of the resonator 32 and the oscillation signal of the oscillator 36 is applied to the oscillator 36 by locking the phase. As a result, the phase detector 33 inputting the oscillation signal of the oscillator 36 and the gain-controlled signal of the AGC 29 detects the phase by comparing the two signals. The second low pass filter 34 which inputs the phase signal detected by the phase detector 33 filters and outputs an error component.

FIG. 5 is a detailed circuit diagram of the phase detector 33 of FIG. 3, which comprises a comparator 41 for inputting an oscillation signal from the oscillator 36 and comparing it with a reference voltage, a comparison output signal of the comparator 41 and an AGC ( And a moving signal demodulation section 42 for demodulating the moving picture signal by inputting the gain-adjusted signal of 29).

6 is an output waveform diagram of the video signal demodulator 42 of FIG.

An embodiment of the present invention based on the configuration described above with reference to FIGS. 5-6, a comparator for inputting the oscillation signal from the oscillator 36 to the non-inverting terminal (+) and the reference signal to the inverting terminal (-) Reference numeral 41 compares the two signals and outputs a pulse signal. The moving signal demodulation section 42, which inputs the pulse signal of the comparator 41 and the gain-controlled signal of the AGC 29, holds the moving signal to hold the moving signal, and when the phase is 0 degrees as shown in FIG. If it is 90 ° phase, it becomes the middle (M) level, and if it is 180 ° phase, it becomes the “L” level.

As described above, the video cassette recorder detects a moving picture signal and records and reproduces the tape on a single carrier by phase modulation to prevent an error caused by jitter and noise.

Claims (3)

In a moving picture recording system of a video cassette recorder, an analog / digital converter (1) for inputting an analog composite video signal to convert a digital composite video signal, and an output digital video signal from the analog / digital converter (1) The frame memory 2 for delaying and outputting one frame, the digital video composite video signal of the analog-to-digital converter 1 and the one-frame delayed signal that is the output of the frame memory 2 are inputted to the two signals. Adder (3) for detecting the moving picture signal by comparing with and the rectifier (4) for taking the moving picture signal detected from the adder (3) as an absolute value, and the signal taking the absolute value from the rectifier (4) A low pass filter 5 for limiting a band, an oscillator 8 for generating a predetermined oscillation frequency, and a frequency for dividing a frequency generated in the oscillator 8 1-9 phase shifters 10-13 for shifting different phases by inputting the period 9, the divided signals of the divider 9, respectively, and the band-limited in the low pass filter 5; A lock-up table 20 for inputting a signal and outputting a selection signal of the phase shifters 10-13, a sync separator 6 for inputting a composite video signal to separate sync, and a sync separator 6 A mono multivibrator 7 for inputting a synchronously separated signal to adjust the duty, and one of the phase shifters 10-13 by an output signal of the lockup table 20 to select the mono vibrator 70 A switch 14 for switching and outputting in the blocking period of the synchronization signal whose duty is adjusted, a Y / C separation unit 15 for separating the luminance signal Y and the color signal C from the composite video signal, A luminance signal processor for FM-modulating the luminance signal Y, which is the output of the Y / C separator 15, 16), a color signal processing unit 17 for modulating and outputting the low-conversion color signal C output from the Y / C separation unit 15, and the outputs of the luminance signal processing unit 16 and the color signal processing unit 17. And a mixer 18 for mixing the signal and the switch 14 switching selected signal to output the composite video signal, and a preamplifier 19 for amplifying and outputting the composite video signal output from the mixer 18. A moving picture recording system using a video cassette recorder. In a system for reproducing a moving picture signal in a video cassette recorder, a preamplifier 21 for inputting and amplifying and outputting a video signal picked up from the head HD1 and a video signal amplified and output from the preamplifier 21 are inputted. A first low pass filter 22 for filtering and outputting only low-pass color signals, a first band pass filter 23 for filtering and outputting only high-pass luminance signals by inputting an image signal amplified and output from the preamplifier 21, and A first band pass filter 24 for inputting an image signal amplified and output from the preamplifier 21 to filter and output only a carrier of the moving signal, and a filtered low-pass color signal C of the low pass filter 22. A color signal processing unit 25 for demodulating and outputting, a luminance signal processing unit 26 for FM demodulating and outputting the filtered luminance signal Y of the first band pass filter 23, and the color signal processing unit 25 And the luminance signal processing A mixer 27 for mixing the outputs of the outputs 26 and outputting the composite video signal, a synchronization separator 28 for separating the synchronization by inputting the FM demodulated signal which is the output of the luminance signal processor 26, and The gain is adjusted by the moving band carrier signal filtered by the second band pass filter 24 to adjust the duty by inputting the separated synchronization signal of the automatic gain controller 29 and the synchronization separator 28. A reference for detecting the reference signal of the moving picture carrier by passing the output signal of the AGC 29 during the blacking period of the mono multi vibrator 30 and the synchronization signal whose duty value is adjusted in the mono multi vibrator 30 A signal detector 31, a resonator 32 for resonating the reference signal of the moving picture carrier detected by the reference signal detector 31, an oscillator 36 for generating a reference frequency, and the resonator 32 Resonant signal and oscillator 36 oscillation A phase synchronization loop circuit 35 for inputting a signal to lock the phase, a phase detector 33 for inputting an output signal of the automatic gain controller 29 and an output signal of the oscillator 36 to detect a phase; And a second low pass filter (34) for filtering the phase detected signal of the phase detector (33) to remove error components. The comparator 41 according to claim 2, wherein the phase detector 33 inputs an oscillation signal from the oscillator 36 and outputs a pulse signal in comparison with a reference voltage, and an output signal and an automatic gain controller of the comparator 41. And a video signal demodulator (42) for demodulating the video signal by inputting the gain-adjusted signal of (29).

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