JP3072260B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR (Video
o Tape Recorder), and more specifically, a recording signal in which the positional relationship between a chroma signal and a synchronizing signal such as a dubbing-recorded reproduction signal or a soft tape reproduction signal is shifted as a recording signal. The present invention relates to a magnetic recording / reproducing apparatus that suppresses the occurrence of horizontal chroma noise in a reproduced image.

[0002]

2. Description of the Related Art A conventional magnetic recording and reproducing apparatus of this kind is
Those capable of recording / reproducing TSC and PAL signals will be described below with reference to FIGS. Here, FIG. 2 is a block diagram showing a schematic configuration of a recording system in the conventional magnetic recording / reproducing apparatus, and FIG. 3 is a block diagram showing a schematic configuration of a reproducing system in the conventional magnetic recording / reproducing apparatus.

In FIG. 2 showing a recording system in a conventional magnetic recording / reproducing apparatus, reference numeral 1 denotes an auto gain control circuit (hereinafter referred to as an auto gain control circuit) for controlling an input video signal (recording reproduced video signal during dubbing) to an appropriate gain. , AGC circuit), 2 is a low-pass filter (hereinafter referred to as LPF) for extracting a recording luminance signal, 3 is a clamp circuit that clamps the leading end level of the synchronization signal to a constant voltage, and 4 is a clamp circuit. A pre / emphasis circuit 5 for emphasizing a waveform is a white / dark which appropriately clips a preshoot component or an overshoot component on a white peak side and a leading end side of a synchronization signal in order to prevent overmodulation of a pre-emphasized recording luminance signal.・ Clip circuit 6, FM for recording luminance signal
This is an FM modulation circuit for performing modulation.

[0004] Reference numeral 7 denotes a sync separation circuit for separating a sync signal from the output of the clamp circuit 3, and 8 denotes an E-D signal based on the timing of the sync signal separated by the sync separation circuit 7.
An on-screen display circuit (hereinafter referred to as O) for superimposing and outputting an E signal (through signal to a monitor)
SD circuit).

[0005] Reference numeral 9 denotes a band-pass filter (hereinafter, referred to as BPF) for extracting a recording chroma signal, and 10 denotes an auto-chroma control circuit (hereinafter, an ACC circuit) that keeps the amplitude of the recording chroma signal constant. , A low-band conversion circuit 11 for performing predetermined low-band chroma signal conversion processing;
Is a low-band chroma signal (NTSC: 629 kHz, PAL:
627 kHz). P. F. , 13 are L.P.
P. F. This is a mix circuit that mixes the low-band chroma signal that has passed through 12 with the recording luminance signal after FM modulation, and outputs the mixed signal to the subsequent recording amplifier (not shown).

In FIG. 3 showing a reproducing system in a conventional magnetic recording / reproducing apparatus, reference numeral 21 designates a head amplifier circuit for amplifying an input video signal (for example, a reproduced dubbing-recorded video signal) to a predetermined level; Reference numeral 22 denotes a high-pass filter (hereinafter, referred to as a high-pass filter) for extracting a reproduction luminance FM signal.
H. P. F), 23 is a reproduction FM equalizer circuit for correcting reproduction frequency characteristics, 24 is a double limiter circuit for suppressing the black-and-white inversion phenomenon, and 25 is an FM demodulation circuit for converting a reproduction luminance FM signal to a reproduction luminance signal. It is.

Reference numeral 26 denotes a de-emphasis circuit for applying de-emphasis having a characteristic opposite to the pre-emphasis at the time of recording.
27 is a noise canceller circuit for suppressing noise included in the reproduced luminance signal, 28 is a synchronization separation circuit for separating the synchronization signal, and 29 is a specified H for the timing of the synchronization signal separated by the synchronization separation circuit 28. (Horizontal scanning period)
A burst gate pulse generation circuit that generates a burst gate pulse at a timing delayed by an interval.

[0008] L.30 takes out the reproduced chroma signal. P.
F. , 31 are ACC to keep the amplitude of the reproduced chroma signal constant
A circuit 32 is an auto phase control circuit (hereinafter referred to as an APC circuit) for correcting the phase of the burst signal in the reproduced chroma signal with the burst gate pulse width, and a predetermined high frequency chroma signal conversion process 33 is performed. The high-frequency conversion circuit 34 passes the reproduced chroma signal subjected to the high-frequency conversion. P. F. , 35 are the reproduced chroma signal and the noise
This is a mix circuit that outputs the reproduced luminance signal from the canceller circuit 27 to an OSD circuit or a video output terminal (not shown) at the subsequent stage.

In the above configuration, if the timing of the burst signal inputted to the APC circuit 32 and the timing of the burst gate pulse are shifted, the phase correction of the burst signal becomes insufficient, resulting in chroma noise of horizontal pulling. Will appear on the screen.

For this reason, in the reproducing system of the conventional magnetic recording / reproducing apparatus, the input signal system (NTSC or PSC) is used.
AL) corresponding to the NTSC / PAL switching signal,
By driving the changeover switch 36 to switch the resistance 37 between the ground side and the non-ground side, the APC circuit 32
By switching the time constant of the above, the phase lock timing of the burst signal extracted by the burst gate pulse is shifted, thereby suppressing the occurrence of the horizontal chroma noise.

[0011]

However, in the above-mentioned conventional magnetic recording / reproducing apparatus, since the recording luminance signal is pre-emphasized in the recording system, the position of the burst signal relative to the synchronizing signal in the reproduced signal is the normal position. In many cases, it is difficult to correct this shift by changing the time constant of the APC circuit 32 in the reproduction system, and there is a problem that it is impossible to completely suppress the occurrence of chroma noise due to horizontal pulling. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and a recording system corrects the position of a burst signal with respect to a synchronizing signal in a recording chroma signal, thereby generating horizontal chroma noise. It is an object of the present invention to provide a magnetic recording / reproducing apparatus that can effectively suppress the occurrence of the magnetic field.

[0013]

A magnetic recording / reproducing apparatus according to the present invention comprises a burst extracting means for extracting a burst signal from a recorded video signal, and a burst having a regular timing based on a synchronization signal separated from the recorded video signal. A normal timing burst signal generating means for generating a signal, a burst signal extracted by the burst extracting means, and a timing of a normal timing burst signal generated by the normal timing burst signal generating means; Comparing means for outputting a timing correction signal corresponding to the comparison result; and a burst gate for generating a burst gate pulse based on the synchronization signal separated from the recording video signal and the timing correction signal from the comparing means. .Pulse generation means and the burst gate pulse generation means On the basis of the burst gate pulse, those formed by providing a burst position correcting means for correcting the position of the burst signal in the recording chroma signal.

Further, in the magnetic recording / reproducing apparatus of the present invention, the shift of the burst signal position with respect to the synchronization signal in the recording chroma signal can be corrected in the recording system. It becomes possible to suppress it.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetic recording / reproducing apparatus according to the present invention will be described below with reference to FIG. 1. The same parts as those in the above-described conventional example are denoted by the same reference numerals, and description thereof will be omitted. Further, the reproducing system in the magnetic recording / reproducing apparatus of the present embodiment is the same as the above-described conventional example, and therefore, only the recording system will be described. Here, FIG. 1 is a block diagram showing a schematic configuration of a recording system in the magnetic recording / reproducing apparatus of the present embodiment.

The magnetic recording / reproducing apparatus according to this embodiment is similar to the conventional magnetic recording / reproducing apparatus described above with reference to FIG. P. F. 2, a burst extraction circuit 41 for extracting a burst signal from the input of the second input, and a normal timing for generating a burst signal of a normal timing at a timing position delayed by a specified H interval with respect to the timing of the synchronization signal separated by the synchronization separation circuit 7 An OSD circuit 42 having a built-in burst signal generation circuit is compared with a burst signal extracted by the burst extraction circuit 41 and a normal timing burst signal from the OSD circuit 42 to determine a width corresponding to a timing shift between both inputs. And a comparator 43 for generating the timing correction signal of

Further, a burst gate pulse generating circuit 44 for generating a burst gate pulse based on the timing correction signal from the comparator 43 and the synchronizing signal from the synchronizing separation circuit 7; A burst position correction circuit 45 for muting with the burst signal extracted by the burst extraction circuit 41 and re-adding a burst signal based on the burst gate pulse from the burst gate pulse generation circuit 44. ing.

In the above configuration, the normal timing burst signal generation circuit is built in the OSD circuit 42 because the OSD circuit 42 has a so-called blue-back function for displaying the entire monitor on a blue screen. Since a VCO circuit for generating a burst signal is provided for this purpose,
This is to generate a burst signal of normal timing using this VCO circuit.

In the recording system of the magnetic recording / reproducing apparatus configured as described above, the burst extracting circuit 41 uses the L.V. P. F. The burst signal is taken out from the input of 2 and output to the comparator 43 and the burst position correction circuit 45. On the other hand, the OSD circuit 42 generates a burst signal of normal timing at a timing delayed by a prescribed H interval with the synchronization signal separated from the output of the clamp circuit 3 as a reference timing, and outputs the burst signal to the comparator 43. .

The comparator 43 compares the respective timings of the burst signal extracted by the burst extraction circuit 41 and the normal timing burst signal from the OSD circuit 42, and generates a timing correction signal having a width corresponding to the timing deviation. To the burst gate pulse generation circuit 4
4 is output. Burst gate pulse generation circuit 44
Then, a burst gate pulse based on the width of the timing correction signal is generated using the synchronization signal from the synchronization separation circuit 7 as a reference timing, and is output to the burst position correction circuit 45.

In the burst position correction circuit 45,
After the recording chroma signal from the ACC circuit 10 is once muted by the burst signal from the burst extracting circuit 41, the burst signal is added again based on the timing of the burst gate pulse, and the low level signal of the next stage is added. It outputs to the area conversion circuit 11.

As described above, in the magnetic recording / reproducing apparatus of this embodiment, the recording system corrects the shift of the burst signal position with respect to the synchronizing signal in the recording chroma signal, and mixes with the recording luminance FM signal for recording. As a result, the phase correction effect in the APC circuit in the reproduction system can be enhanced thereafter, and the occurrence of chroma noise due to horizontal subtraction can be effectively suppressed.

[0023]

Since the magnetic recording / reproducing apparatus of the present invention has the above-described configuration, the recording system can correct the shift of the burst signal position with respect to the synchronization signal in the recording chroma signal. Can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a recording system in an embodiment of a magnetic recording / reproducing apparatus of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a recording system in a conventional magnetic recording / reproducing apparatus.

FIG. 3 is a block diagram showing a schematic configuration of a reproducing system in a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

1 AGC circuit 2 L. P. F. 3 Clamp circuit 4 Pre-emphasis circuit 5 White / dark clip circuit 6 FM modulation circuit 7 Sync separation circuit 9 B. P. F. 10 ACC circuit 11 Low frequency conversion circuit 12 L. P. F. 13 mix circuit 41 burst extraction circuit 42 OSD with built-in regular timing burst signal generation circuit
Circuit 43 Comparator 44 Burst gate pulse generation circuit 45 Burst position correction circuit

Claims (1)

(57) [Claims] 1. A burst extracting means for extracting a burst signal from a recording video signal, and a synchronizing signal separated from the recording video signal,
A normal timing burst signal generating means for generating a normal timing burst signal; a burst signal extracted by the burst extracting means; and a regular timing burst signal generated by the normal timing burst signal generating means. Comparing means for comparing timings and outputting a timing correction signal according to the comparison result; and a burst signal based on the synchronization signal separated from the recording video signal and the timing correction signal from the comparing means.
Burst gate pulse generating means for generating a gate pulse, and a burst position for correcting the position of the burst signal in the recording chroma signal based on the burst gate pulse generated by the burst gate pulse generating means A magnetic recording / reproducing apparatus comprising a correction unit.