KR960008997B1 - Fm color recording and playing circuit of image recorder and player - Google Patents

Abstract

The circuit includes an auto-gain controller(103) for auto-controlling the gain of a video signal, an Y/C seperator(105) for seperating the video signal into a luminance signal and color signal, a first luminance signal processor(111) for outputting by FM-modulating the luminance signal, a first color signal processor(113) for low-band-converting the color signal, a FM color processor for outputting by FM-modulating the color signal, and a pre-amplifier(117) for inputting, mixing and amplifying the output signals of the first luminance signal processor(111), first color processor(113) and FM color processor and recording them on a tape through a recording head(123).

Description

FM color recording and playback device for video recorder

1 is a recording circuit diagram of a conventional video recording and reproducing apparatus.

2 is a reproduction circuit diagram of a conventional video recording player.

3 is a block diagram of an FM color recording circuit according to the present invention.

4 is a detailed view of the FM color processor of FIG.

5 is a block diagram of an FM color reproduction circuit according to the present invention.

6 is a detailed circuit diagram of the FM color processor of FIG.

7 is a frequency spectrum diagram of FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal recording and reproducing circuit of an image recording and reproducing apparatus, and more particularly to a circuit for AM FM modulation of a color signal, recording on a magnetic tape, and selectively extracting and reproducing the recorded color signal.

The recording circuit of the conventional video recording / reproducing apparatus includes an automatic gain control (AGC) 3 for adjusting and outputting a gain of an input video signal as shown in FIG. A Y / C separator 5 for inputting a gain-adjusted video signal, i.e., a composite video signal, and outputting them separately to the luminance signal Y and the color signal C, and the luminance output from the Y / C separator 5 separately. A luminance processing unit 11 for FM-modulating and outputting the signal 5, a color processing unit 13 for low-converting and AM-modulating and outputting a color signal output from the Y / C separator 5 into a 629 KHz signal, and A preamplifier 14 for inputting and amplifying and outputting the signals of the luminance processor 11 and the color processor 13, and a head 15 for recording the signals of the preamplifier 14 on a tape.

When a video signal is input to the input terminal 1 of the AGC 3, the AFC 3 automatically adjusts the readout and then inputs it to the Y / C separator 5. The Y / C separator 5 separates the video signal from the luminance signal Y and the color signal C and outputs the video signal. In this case, the separated luminance signal Y is FM-modulated by the luminance processor 11 and outputted, and the color signal C is low-frequency converted to 629 KHz by the color processor 13 and AM-modulated. The preamplifier 14 which inputs the luminance signal Y and the color signal C which are processed and output from the luminance processor 11 and the color processor 13, respectively, is mixed and amplified and input to the recording head 15. The recording head 15 records this on the tape. The conventional reproducing circuit for picking up and reproducing the video signal recorded by the operation of the above circuit is as shown in FIG.

2 is a reproducing circuit diagram of a conventional video recording and reproducing apparatus, wherein a reproducing head 17 picks up and outputs a video signal recorded on a tape and a pre-amplifying signal of the reproducing head 17 with a sufficient signal. An amplifier 19, a first band pass filter (hereinafter referred to as BPF) 21 for filtering and outputting only a band of an FM modulated luminance signal among video signals output from the preamplifier 19, and the preamplifier 19 A low pass filter (LPF) 23 for filtering and outputting only the band of the AM low-converted color signal among the signals of the signal and the luminance reproduction processing unit 25 for FM demodulating and outputting the luminance signal Y which is the output of the first BPF 21. ), And a color reproduction processing unit 27 for demodulating and outputting the low frequency transformed color signal by inputting the output of the LPF 23, and mixing the outputs of the luminance reproduction processing unit 25 and the color reproduction processing unit 27 with each other. And a mixer 29 for outputting a video signal.

When the playhead 17 picks up the video signal from the tape in the circuit configured as described above, it is input to the first BPF 21 and the LPF 25, respectively. At this time, the first BPF 21 filters only the band of the modulated luminance signal Y and inputs it to the luminance reproduction processor 23 to demodulate the modulated luminance signal Y and input the demodulated luminance signal Y to the mixer 29. In addition, the LPF 23 filters only the band of the low-pass converted color signal C and inputs it to the color reproducing processor 27. The color reproducing processor 27 demodulates the low-converted color signal C to the mixer. (29). Therefore, the mixer 29 mixes the luminance demodulation signal Y of the luminance reproduction processing unit 25 and the color demodulation signal C of the color reproduction processing unit 27 to output the composite video signal through the output terminal 31. do.

However, the AM modulated color signal obtained by low-converting the color signal C separated from the video signal, which is a composite video signal, with a configuration as shown in FIG. 1 at 629 KHz is recorded on a tape, and the 629 KHz low-pass converted color as shown in FIG. The conventional video signal recording and reproducing circuit which picks up and demodulates signals has a low AM demodulation rate when reproducing color signals. Therefore, there is a problem that the phase of the color signal slightly shifts because the frequency of the color signal low-converted due to jitter shifts slightly in time. Due to the above problems, the signal-to-noise ratio (S / N) is poor when recording and reproducing color signals.

Accordingly, an object of the present invention is to provide a circuit that suppresses phase variation and amplitude variation by maximizing the frequency band by converting 3.5MHz color signal to 629KHz, reducing the frequency band, and then recording with FM-modulated luminance signal. have.

It is another object of the present invention to provide a circuit for low frequency conversion to reduce the frequency band by converting the color signal and then FM modulation, low frequency conversion for the color signal, and separating the frequency band to record on the tape together with the FM modulated luminance signal. .

Another object of the present invention is to provide a playback circuit for filtering and extracting an FM modulated color signal and an FM modulated luminance signal, and outputting a mixed video signal by FM demodulating each signal.

It is still another object of the present invention to filter and extract the FM modulated color signal, the FM modulated luminance signal, and the low frequency transformed color signal to demodulate each of the modulated signals, and to demodulate the demodulated luminance signal and the low frequency transformed color signal or FM. A reproduction circuit for outputting a mixed signal of a demodulated signal of a modulated color signal is provided.

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

FIG. 3 is a block diagram of an FM color recording circuit according to the present invention, wherein reference numeral 103 in the figure automatically adjusts and outputs a gain of a video signal, which is a composite video signal input to the terminal 100 as an automatic transverse edger (AGC). Perform the function. 105 is a Y / C separator that separately outputs a luminance signal (Y) and a color signal (C) for a video signal adjusted automatically. 111 is a first latitude processor, and modulates and outputs the luminance signal Y separated from the Y / C separator 105 to 3.4 MHz at a sink tip and 4.2 MHz at a white clip. Reference numeral 113 denotes a first color processing unit which low-converts the color signal C of 3.58 MHz, which is separated from the Y / C separator 105, to 629 KHz, and outputs an AM modulated color signal. Reference numeral 115 denotes a first band pass filter BPF to filter and output only a band of the FM modulated luminance signal of the first luminance processor 111. Reference numeral 117 denotes an amplified output by mixing an input signal as a first preamplifier, and 123 records an output signal of the first preamplifier 117 as a recording head on a tape (not shown). Reference numeral 119 denotes a second color processing unit, and low-frequency output of a 3.58 MHz color signal output from the Y / C separator 105, such as the first color processing unit 113, into a signal of 629 KHz. It is an FM modulator for FM-modulating a predetermined carrier frequency of the color signal low-converted by the two-color processing unit 199.

FIG. 4 is a detailed view of the FM color processor of FIG. 3, which shows a detailed view of the second color processor 119 and the FM modulator 121 in the dotted block A. As shown in FIG.

In FIG. 4, reference numeral 303 designates a gain of the color signal by a predetermined control signal in order to improve the S / N ratio of the color signal C inputted as an automatic color gain control (ACC). Circuit. The 305 is a balance modulator, which inputs an auto gain-adjusted 3.58 MHz color signal and a 4.2 MHz subcarrier, and performs balanced modulation to low-convert the color signal to a 629 KHz signal. Reference numeral 307 denotes a burst gate and extracts and outputs only the burst signal of the color signal C. 309 denotes an ACC detection unit that detects the level of the burst which is an output of the burst gate 307. Control signal 303). Reference numeral 311 denotes a first divided output of the burst gate 307 as a first divider. Reference numeral 313 denotes a voltage controlled oscillator (VCO) which oscillates a subcarrier of 4.2 MHz by a predetermined control voltage and inputs it to the balance modulator 306. Reference numeral 315 denotes a second divider to divide and output the oscillation output of the voltage controlled oscillator 303. Reference numeral 317 denotes a phase comparator and compares the output of the first divider 311 and the output of the second divider 315 to input the voltage of the phase comparison to the voltage controlled oscillator (VCO) 313. . Reference signal 319 is a band pass filter (BPF) to filter and output only the low-conversion color signal (C) output from the balance modulator 305, 121 is an FM modulator as a subcarrier (fc) of 7.3MHz FM signal Modulate output.

5 is a block diagram of an FM color reproduction circuit according to the present invention, where 125 is a head for picking up a recording signal recorded on a tape, and 127 is a second preamplifier to amplify the pickup output of the head 125. Output Reference numeral 129 denotes a second band pass filter (BPF) that filters and outputs only the FM-modulated 3.4 MHz to 4.2 MHz luminance signal C band among the output signals of the preamplifier 127. Reference numeral 131 denotes an LPF, a filter for filtering and outputting only the color signal C low-converted to 629 KHz among the output signals of the preamplifier 127, and 133 an output of the preamplifier 127 as a high pass filter (HPF). Only the color signal C modulated by the subcarrier of 7.3 MHz among the signals is filtered out. Reference numeral 135 denotes a second luminance processor and FM demodulates the FM modulated luminance signal C, which is a filtering output of the second BPF 129, and reference numeral 137 denotes a filtering output of the LPF 131 as a third color processor. AM demodulation of the low-conversion color signal C outputs a color signal. Reference numeral 139 denotes an FM demodulator for outputting the FM demodulated output as the fourth color processor. Reference numeral 141 denotes a selection switch that selects and outputs one of the outputs of the third and fourth color processing units 137 and 139 according to the selection switching state. Reference numeral 143 denotes a mixer which mixes the outputs of the second luminance processing unit 135 and the selection switch 141 and outputs a composite image signal, that is, a video signal, as an output terminal.

FIG. 6 is a detailed view of the FM color processing section of FIG. 5, which is a detailed view of the HPF 133 and the fourth color processing section 139 in the dotted block B shown in FIG.

In FIG. 6, reference numeral 133 denotes an HPF and performs a function as described above in FIG. The 405 demodulates the high-pass filtered FM modulated signal as an FM demodulator and outputs a 629 KHz low-conversion signal, and 407 filters only the low-conversion signal of 629 KHz as an LPF. 409 is an ACC, and a low frequency converted color signal is automatically gain-adjusted by a predetermined control signal, and 411 is a parallel modulator for outputting a color signal of 3.58 KHz by performing a parallel modulation of the low frequency converted color signal C by a predetermined subcarrier. to be. 413 denotes a BPF and filters and outputs a color signal of 3.58 MHz, which is an output of the parallel modulator 411. 415 detects the level of the burst pulse in the color signal C output from the BPF 413 as a burst detector, inputs a control signal of the ACC 409 and outputs a burst. Reference numeral 417 divides and outputs a burst pulse output from the burst detector 415 as a first divider. 419 is a voltage controlled oscillator (VCO) that oscillates a frequency by a predetermined control voltage and serves to input the balance modulator 411. 421 denotes a second divider and outputs the oscillation output of the VCO 419 by a predetermined division. 423 denotes a phase comparator to compare the phases of the outputs of the first and second dividers and control the phase difference voltage of the VCO 419. Input by voltage.

FIG. 7 is a frequency spectrum diagram of FIG. 3, where FIG. 7a is a spectrum of the band of the color signal C of 3.58 MHz, and FIG. 7b is a frequency spectrum diagram when the low frequency conversion of the 3.58 MHz signal is performed at 629 KHz. . 7c is a frequency spectrum diagram of the FM modulated color signal when FM modulation of the low-conversion color signal (C) of 629 KHz is performed as a subcarrier of 7.3 MHz, and 7d is an FM modulated color signal and an FM modulation color signal of a low-conversion color signal of 629 KHz at the time of recording. Frequency spectrum diagram of the modulated luminance signal.

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

When the composite video signal and the video signal are input to the terminal 100, the gain is automatically adjusted by the AGC 103 and then input to the Y / C separator 105. The Y / C separator 105 separates the video signal from the luminance signal Y and the color signal C as shown in FIG. 7A and outputs the same through the output lines 107 and 109. At this time, the signal through the output line 107 is FM-modulated by the luminance signal processing unit 111, and the color signal (C) through the line 109 is a low-frequency conversion of the signal at 629KHz by the color processing unit 13 and outputs it. .

In addition, the signal input through the line 109 is input to the burst gate 307 at the same time as the gain of the color gain is controlled by the predetermined control in the ACC 303 of FIG. The burst gate 307 extracts only the burst signal from the input 3.58 MHz color signal C and inputs the burst signal to the first divider 311 and the ACC detector 309. The ACC detector 309 detects the level of the burst pulse and inputs a control signal of the ACC 303 to a signal having a predetermined level, and the first divider 311 divides the input burst signal into a predetermined phase comparator 317. To enter. At this time, the phase comparator 317 phases the output of the second divider 315 and the divided output of the first divider 311 by dividing the oscillating output of the VCO 313 that oscillates a sine wave signal of 4.2 MHz. In comparison, the phase difference signal is input to the control signal of the VCO 313. Therefore, the burst is extracted from the 3.58 MHz color signal and the divided signal is compared with the divided signal of the VCO 313 to control the VCO 313 so that the oscillation signal of the color signal and the VCO 313 are out of phase. Locking).

On the other hand, the balance modulator 305 for inputting a 3.58 MHz color signal C is modulated by parallel modulation of the color signal C by a subcarrier of 4.2 MHz, which is oscillated and output from the VCO 313, which is the frequency of the difference. Outputs a 629KHz low-conversion signal and a 7.8MHz color modulated signal. The modulated signal of the parallel modulator 305 is filtered by the BPF 319 that filters only the band signal of 629 KHz, so that only the low-converted 629 KHz signal is input to the FM modulator 121 as shown in FIG. The FM modulator 121 inputs the low frequency converted color signal into a 629 KHz signal, and FM modulates the frequency of 0.4 MHz into a shifted signal as shown in FIG. 7C by the input subcarrier fsc (7.3 MHz). 117). The sideband has a frequency range of 6.2MHz to 8.4MHz. Accordingly, the FM modulated signal having the frequency deviation of the sync tip 3.4 MHz and the white clip 4.4 MHz from the first luminance processor 111 is filtered by the first BPF 115, and the luminance signal Y and the first color processor 113 are adjusted. The AM-modulated color signal C, which has been low-converted at, and the preamplifier 117 inputting the modulated output signal from the FM color modulation 121 are mixed and amplified and output to the head 123. Therefore, the frequency spectrum recorded on the tape by the head 123 becomes as shown in FIG. Therefore, both the FM modulated luminance signal Y, the low frequency converted color signal C, and the low frequency converted FM signal modulated color signal C are recorded on the recording tape.

When the image signal recorded as described above is picked up from the head 125 of FIG. 5, the signal picked up from the head 125 is amplified by the second preamplifier 127 and then the second BPF 129 and the LPF ( 131 and HPF 133 are input. At this time, the second BPF 129 filters only the band of the modulated luminance signal Y and inputs the same to the second luminance signal processor 135 to demodulate the FM modulated luminance signal Y and input the same to the mixer 143. 23 is input to the color processing unit 27 by filtering only the band of the low-frequency conversion color signal (C) only, and input to the color signal processing unit 27, the color signal processing unit 27 is the low-frequency conversion The color signal C is demodulated and input to one end of the selection switch 141.

The HPF 133 filters only the FM color signal band FM-modulated at 7.3 MHz among the signals amplified and output from the preamplifier 127 to the FM demodulator 405 in the fourth color processing unit 139 configured as shown in FIG. Enter it. At this time, the FM demodulator 405 demodulates the FM modulated color signal and filters the low frequency conversion color signal of 629 KHz through the LPF 407 and inputs it to the ACC 409. The ACC 409 adjusts the gain of the low-frequency conversion color signal demodulated at 629 KHz to the balance modulator 411 by adjusting the gain by predetermined control. The balance modulator 411 modulates a 629 KHz low-conversion color signal of 3.58 MHz by the 4.2 MHz subcarrier oscillated and output from the VCO 419 and outputs the color signal of 3.58 MHz to the BPF 413. The BPF 413 bandpass filters only signals of the 3.58MHz band and outputs them to the burst detector 415 and outputs them to the tartan of the selection switch 141.

On the other hand, the burst detector 415 for inputting the 3.58 MHz color signal filtered out of the BPF 413 detects the burst pulse level to supply the gain control signal of the ACC 409 and simultaneously provides the burst signal to the first signal. The frequency divider 417 is input. The first divider 417 divides the input burst signal into a predetermined phase comparator 423. At this time, the phase comparator 423 compares the phase of the first divider 417 with the output of the second divider 421 for dividing the half-output output of the VCO 419 by a predetermined frequency, and the VCO as a signal of the phase difference. By controlling 419, the 4.2MHz VCO 419 output is synchronized with the phase of the color signal.

As described above, when the selection switch 141 selects the signal of the fourth color processing unit 137 in a state in which the third and fourth color processing units 137 and 139 are demodulated and output, respectively, the mixer unit 143 makes an AM signal. The demodulated color signal and the FM demodulated luminance signal are mixed to output a composite video signal. When the selection switch 141 selects the signal of the third color processing unit 139, the mixer 143 and the FM demodulated color signal are combined. The composite video signal mixed with the FM demodulated luminance signal is outputted to the terminal 145. Therefore, the FM-modulated luminance signal, the low-converted color signal, and the low-converted color-modulated color signal are recorded on the tape, and during playback, the composite video signal obtained by mixing the low-conversion color signal and the demodulated signal of the FM-modulated signal or The video signal can be selected based on the demodulated signal sum of the FM modulated color signal and the FM modulated luminance signal.

As described above, the present invention has the advantage that the signal-to-noise ratio of the color signal is improved by reducing the phase and amplitude fluctuation range of the color signal to the maximum by performing FM modulation by low-converting the color signal while having compatibility with the existing video recording and reproducing apparatus. .

Claims (3)

In the FM color recording circuit of a video recording and reproducing apparatus, an automatic gain controller (103) for automatically adjusting the gain of a video signal and a video signal output from the gain control output from the automatic gain controller (103) are separated into a luminance signal and a color signal. Y / C separator 105, first luminance processor 111 for FM modulation output luminance signal separated from Y / C separator 105, and color separated and output from Y / C separator 105 A first color processor 113 for low-conversion and outputting the signal, an FM color processor for low-converting the separated color signal to perform FM modulation on a predetermined subcarrier, and the first luminance processor 111 and the first luminance processor; FM color recording of a video recording player, characterized in that it comprises a preamplifier 117 for input mixing, predetermined amplification of each output of the color processing unit 113 and the FM color processing means, and recording on a tape through the recording head 123. Circuit. The FM color processing means according to claim 1, characterized in that the automatic color gain adjuster (303) for adjusting the gain of the color signal in response to the input of the control signal, and the burst of the color signal output from the automatic color gain adjuster (303). Oscillating means for detecting a signal level to provide a control signal of the automatic color gain regulator 303 and oscillating and outputting a subcarrier synchronized with the phase of the color signal, and the automatic color gain regulator 303 by the subcarrier of the oscillating means. A balanced modulator 305 for performing low frequency conversion by parallel modulating the color signal output of the < RTI ID = 0.0 >), < / RTI > and an FM modulator 121 for filtering the output of the balanced modulator 305 and performing FM modulation on a predetermined subcarrier fc. FM color recording circuit of a video recording and reproducing apparatus. In the FM color reproduction circuit of the video recording and reproducing apparatus, a second preamplifier 127 for amplifying the output of the head 125 for picking up a signal recorded on a tape, and an output signal of the second preamplifier 127, respectively; A second band pass filter 129, a low pass filter 131, and a high pass filter 133 which are inputted and filtered by signals of an FM luminance modulation band, a low frequency conversion color signal band, and an FM modulation color signal band, respectively; A second luminance processor 135 for demodulating and outputting an FM modulated luminance signal output from the second band pass filter 129, and a low-pass color signal output from the low pass filter 131 as a color signal. A fourth color processor 137 for outputting and a FM modulated color signal output from the high pass filter 133 to extract the low frequency transformed color signal and balance modulated by a predetermined subcarrier to output the color signal Color processing unit 139, the image The output of the mixer 143 and the third and fourth color processing units 137 and 139 is converted into a video signal by mixing the second luminance processing unit 135 with the demodulated color signal in a predetermined state. A selector switch 141 which is selected by the controller 143 and inputs the input signal to the mixer 143, wherein the color signal processing the output of the low pass filter 131 and the color signal processing the output of the high pass filter 133 And a selection signal and an output of the second luminance processing unit 135 to reproduce a composite video signal.

Images