JP3158362B2 - Variable speed playback signal processing circuit of playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a variable speed reproduction processing circuit of a reproduction apparatus such as a VTR.

[0002]

2. Description of the Related Art FIG. 7 shows how a track is reproduced by a VTR head at the time of variable speed reproduction of an azimuth recording VTR, for example. At this time, the RF waveform reproduced by the VTR head is as shown in FIG. As can be seen from FIG. 8, the level of the reproduced RF waveform when the head traces the track on the reverse azimuth side decreases, and if the level falls below a certain set potential, demodulation cannot be performed, resulting in a noise portion N. The noise portion N is also called a noise bar portion. If the signal that has become the noise portion N is output as it is, SYNC
(Synchronization) Synchronization of the monitor image is disturbed due to lack (loss), and the noise portion N becomes unsightly due to an increase in white spots. Conventionally, the reverse azimuth track side is traced by a double azimuth head, switched to the one having a larger RF waveform level and reproduced, and a noise bar portion, also called a noise portion N, is eliminated as much as possible. There is.

(1) In order to couple two head chips to the same base member, there is no flexibility in the shape of the head.
C / N deteriorates. (2) Since the number of heads increases and the structure becomes complicated, the cost increases. (3) During variable speed reproduction, a signal processing circuit including a CCD circuit and the like for correcting a time difference when two heads are switched becomes complicated, and the cost is increased. Therefore, because of these problems, the RF envelope detection outputs are compared by a comparator to obtain the D envelope shown in FIG.
A method is employed in which this noise portion N of the demodulated video signal is replaced with a fixed potential using a pulse such as an O DET pulse (detection pulse) output when the RF waveform level falls below a certain value.

[0004]

However, this DO D
Before and after the ET pulse, a large number of fluctuating pulses IR are generated as shown in FIG. 9, and before and after the replacement portion of the monitor screen, defects called white ball noise and replacement flaws occur, leading to deterioration in image quality. In addition, the noise portion N lacks SYNC (synchronization), and if output is performed as it is, synchronization is disturbed. The fluctuation pulse IR occurs in this manner because of the fluctuation of the RF waveform level, especially the change of the spacing, the fluctuation of the tension of the tape, and the like.
This is due to servo fluctuations and differences in RF waveform levels for each horizontal synchronization frequency.

Therefore, the present invention suppresses the fluctuation of the detection pulse in the dropout portion of the reproduction signal before and after its rise and fall, prevents the video signal from being disturbed before and after the replacement, and obtains an excellent image quality. An object of the present invention is to provide a variable speed reproduction processing circuit of a recording VTR.

[0006]

According to the first aspect of the present invention, a recording medium on which information signals are recorded on each inclined track is transported at a transport speed different from the transport speed at the time of recording. In a variable speed reproduction signal processing circuit of a reproducing apparatus adapted to perform reproduction by a rotary magnetic head, a dropout portion of a reproduction signal reproduced by the rotary magnetic head is detected, and a first signal corresponding to the dropout portion is detected. And a second dropout having a pulse width including a fluctuation pulse generated before and after the first dropout detection pulse. This is achieved by a variable-speed reproduction signal processing circuit of a VTR including a substitution means for substituting and outputting a detection pulse signal.

According to the second aspect of the present invention, there is provided a rotating magnetic head which transports a recording medium on which information signals are recorded on each inclined track at a transport speed different from the transport speed at the time of recording. In the variable speed reproduction signal processing circuit of the reproducing apparatus which performs the reproduction by the method, a dropout portion of the reproduction signal reproduced by the rotary magnetic head is detected, and a first dropout detection corresponding to the dropout portion is performed. Dropout detection means for outputting a pulse; and replacing the first dropout detection pulse with a second dropout detection pulse having a pulse width including a fluctuation pulse generated before and after the first dropout detection pulse. The output pulse of the drop-out detection means is different from the first drop-out detection pulse. When the pseudo pulse occurs that, this
This can also be achieved by a variable speed reproduction signal processing circuit of a VTR provided with a removing means for removing a pseudo pulse.

[0008]

According to the configuration of the first aspect, when there is a fluctuating pulse before and after the dropout detection pulse detected by the first detecting means, it can be replaced with a signal having a pulse width including the fluctuating pulse. This makes it possible to perform the replacement process on the dropout section together with the fluctuation pulse accompanying the dropout section.

According to the configuration of the second aspect, when there is a fluctuating pulse before and after the dropout detection pulse detected by the first detecting means, it can be replaced with a signal having a pulse width including the fluctuating pulse. As a result, the dropout portion is replaced with the variable pulse accompanying the dropout portion, and even if there is a pseudo pulse that is a dropout pulse, it can be removed without leaving it.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are
Since it is a preferred specific example of the present invention, various technically preferred limitations are added, but the scope of the present invention is limited to the following description unless otherwise specified to limit the present invention.
It is not limited to these embodiments.

FIG. 1 shows a preferred embodiment of a variable speed reproduction signal processing circuit of a reproduction apparatus according to the present invention. An AGC circuit (automatic gain control circuit) is provided at the input terminal 10 of the processing circuit of FIG.
12 and a DO DET circuit (DO detection circuit) 14 are connected. Between the two input terminals of the DO DET circuit 14 and the OR circuit 16, an integrating circuit 18 and an MMV circuit (mono-multi circuit) 20 are provided. DO DET circuit 1
Reference numeral 4 comprises a conventionally used RF envelope detector and comparator.

The input terminal 10 receives a Y-RF waveform (reproduced luminance-RF waveform), and outputs a DO DET pulse P1 shown in FIG. 2A through an AGC circuit 12 and a DO DET circuit 14. The DO DET pulse P1 has the fluctuation pulse IR before and after the rising and falling of the pulse as described above. DO DET pulse P1 is
A pulse of the falling integration output P2 shown in FIG. At the same time MM
A DO DET pulse P1 is also input to the V circuit 20, and the falling edge trigger causes a mono-multi output P shown in FIG.
Obtain 3 pulses. When the falling integration output P2 and the mono-multi output P3 take an OR logic by the OR circuit 16, a shaping and DO detection pulse P4 is obtained at the output terminal 22.

As described above, even if the fluctuation pulse IR is included like the DO DET pulse P1, a stable and shaped DO detection pulse (DO DET pulse) P4 can be formed by the processing circuit of FIG. . This gives R
The boundary of the replacement portion shown in FIG. 2D due to the decrease in the F waveform level is stabilized, and the image when JOG / SEARCH or the like is performed has high quality. Also, it is easy to find the cut-in and cut-out at the time of editing. Further, the rising of the DO detection pulse can be performed at high speed, and there is no delay of the replacement pulse. Further, since a double azimuth head is not required, the C / N can be improved by a single head. Furthermore, since a single head is sufficient, the cost reduction effect is great.

By the way, as shown in FIG.
If there is a single dropout pulse (pseudo pulse) P0 in the DET pulse P1 other than the portion corresponding to the noise bar portion N, this portion will also be replaced with a wide pulse width. That is, wide pulses P01, P02, and P03 are generated as shown in FIGS.
For this reason, the quality of the speed-change reproduced image is deteriorated. To solve this problem, FIG. 4 shows a processing circuit as another embodiment of the processing circuit of the present invention. However, the same parts as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

An input terminal 10 has an AGC circuit 12 and a DO
The DET circuit 14 is connected. DO DET circuit 1
4 and the input terminal of the OR circuit 16
8 and an MMV circuit 20 are provided. Further, the data input terminal D of the D-type flip-flop 22 is connected between the input terminals of the MMV circuit 20 and the OR circuit 16. A clock terminal CK of the D-type flip-flop 22 is provided between the DO DET circuit 14 and the falling integration circuit 18.
Is connected. The output terminal of the D-type flip-flop 22 and the output terminal of the OR circuit 16 are connected to the input terminal of the AND circuit 24.

The DO DET circuit 14 outputs a DO DET pulse P1 shown in FIG. The falling integration circuit 18 outputs a falling integration output P2 in FIG. The MMV circuit 20 outputs the mono-multi output P3 in FIG. The OR circuit 16 outputs the shaped DO DET pulse P4 in FIG.

The D-type flip-flop 22 outputs a noise bar portion detection output P5 shown in FIG. 3E triggered by the rising edge of the fluctuation pulse IR of the DO DET pulse P1 shown in FIG. From the AND circuit 24, FIG.
As shown in (F), a shaped DO pulse P6 whose waveform is shaped only in the noise bar portion N is output. Thus, FIG.
The single pulse P03 of (D) can be separated and removed. Here, the clock terminal of the D-type flip-flop 22 may be configured to apply a pulse P2 instead of the pulse P1 in FIG.

The processing circuit shown in FIG. 5 performs the replacement process of the noise bar portion N by using a shaped detection pulse P6 also called a shaped DO DET pulse shown in FIG. The input terminal 40 has a DEMOD circuit (demodulation circuit) 42 and a CLAMP
The switch 46 and the TBC circuit 60 are connected via a circuit (clamp circuit) 44. On the other hand, the input terminal 50
, Through an ACC circuit (automatic tone control circuit) 52, a CONV circuit 54 (conversion circuit) and a MUTE circuit 56.
It is connected to a BC circuit 60 (time base collector circuit).

The TBC circuit 60 is connected to a SYNC INS circuit 62 (synchronization command circuit) and a BURSTINS circuit 64 (burst command circuit). Here, Y-RF
The VIDEO signal P8 after demodulating the signal is clamped by the CLAMP circuit 44, and the noise bar portion N is replaced with a fixed potential by the replacement pulse P4. At the same time, the reproduced chroma signal C is MUTE (erased) in the MUTE circuit 56 so that the replacement portion is not colored. The reproduced chroma signal C is extracted by an LPF (low-pass filter) (not shown), level-controlled by the ACC circuit 52, and converted to a 3.58 MHz chroma signal by the next-stage CONV circuit 54. Although this chroma signal is contained in the MUTE circuit 56, the MUTE circuit 56 may be provided in a stage preceding the CONV circuit 54. The Y-RF waveform signal replaced with the fixed potential and the chroma signal C are suppressed in jitter by the TBC circuit 60, and the SYNC INS circuit 62 and the BURST I
The signal is output to a monitor (not shown) through each of the NS circuits.

With such a configuration, the noise bar portion N is stably replaced in variable speed reproduction, and a monitor image without disturbance in synchronization can be obtained. As described above, during variable speed reproduction of the azimuth recording VTR, a decrease in the RF waveform level when the head traces the track on the reverse azimuth side is detected by detecting the RF waveform envelope, and the demodulated video signal is detected by the detection pulse. The signal is replaced with a fixed potential, and then inserted into the SYNC command circuit and the BURST command circuit and output. At this time, the detection pulse falls,
The fluctuation before and after the rising can be stabilized by performing the waveform processing by combining the integrating circuit, and the disturbance of the video signal before and after the replacement can be suppressed.

FIG. 6 shows an example in which the processing circuit of FIG. 1 and the processing circuit of FIG. 5 are connected. The connection may be made as shown by a broken line.

Incidentally, the present invention is not limited to the above embodiment. For example, instead of replacing the noise portion N with a fixed potential, for example, a field memory or the like is provided in the TBC circuit 60, and writing of data is stopped only in the noise portion N. May be substituted. Furthermore, DODE of FIG.
In order to supply the T pulse P1 also to a dropout detection circuit that detects a dropout signal during normal reproduction, the sensitivity setting of the DODET circuit 14 may be switched between normal reproduction and variable speed reproduction.
Further, it goes without saying that the processing circuit of the above embodiment can also process not only the noise accompanying the variable speed reproduction of the azimuth recording VTR, but also the dropout portion caused by a scratch on the tape.

[0023]

As described above, according to the present invention, the boundary of the replacement part of the RF waveform level corresponding to the noise part becomes clear. Therefore, the boundary of the replacement part due to the decrease in the RF waveform level becomes stable, and the image such as JOG / SEARCH becomes high quality. It is easy to find the cut-in and cut-out during editing. The rising of the detection pulse can be performed at high speed, and there is no delay of the replacement pulse. Further, even if a pulse such as a pseudo pulse different from the noise bar portion is generated, the pulse corresponding to the noise bar portion can be replaced with the pulse corresponding to the noise bar portion, so that the image quality is high.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a variable speed reproduction signal processing apparatus for a VTR according to the present invention.

FIG. 2 is a diagram showing waveforms in the embodiment of FIG. 1 of the present invention.

FIG. 3 is a diagram showing waveforms according to another embodiment of the present invention.

FIG. 4 is a view showing another embodiment of the present invention corresponding to FIG. 3;

FIG. 5 is a diagram showing a processing circuit for processing the shaped DO pulse obtained in FIG. 1;

FIG. 6 is a diagram in which each circuit of FIGS. 1 and 5 is connected;

FIG. 7 is a diagram illustrating a locus of a head with respect to a conventional VTR tape.

FIG. 8 is a diagram showing a reproduced waveform envelope in FIG. 7;

FIG. 9 is a diagram showing a DO DET pulse corresponding to a noise portion N in FIG. 8;

[Explanation of symbols]

 12 AGC circuit 14 DO DET circuit 18 Fall integration circuit 20 MMV circuit P1 DO DET pulse P2 Fall integration output P3 Mono multi output P4 Shaped DO pulse

Claims (6)

(57) [Claims] 1. A variable-speed reproducing apparatus in which a recording medium on which an information signal is recorded on each inclined track is transported at a transport speed different from the transport speed at the time of recording and is reproduced by a rotary magnetic head. A signal processing circuit for detecting a drop-out portion of a reproduction signal reproduced by the rotary magnetic head, and outputting a first drop-out detection pulse corresponding to the drop-out portion; And a second dropout detection pulse signal having a pulse width including a fluctuation pulse generated before and after the first dropout detection pulse. A variable speed reproduction signal processing circuit of a reproduction device, characterized by: 2. A variable-speed reproduction of a reproducing apparatus in which a recording medium on which an information signal is recorded on each inclined track is transported at a transport speed different from the transport speed at the time of recording and is reproduced by a rotary magnetic head. A signal processing circuit for detecting a drop-out portion of a reproduction signal reproduced by the rotary magnetic head, and outputting a first drop-out detection pulse corresponding to the drop-out portion; And a second dropout detection pulse having a pulse width including a fluctuation pulse generated before and after the first dropout detection pulse, and outputting the second dropout detection pulse. when pseudo pulse different from the output pulse to the first drop-out detection pulse is generated, the pseudo path A variable speed reproduction signal processing circuit of a reproduction apparatus, comprising a removing means for removing looseness. 3. An integration circuit for integrating and outputting an output pulse of the dropout detection means, a mono-multi circuit for unifying and outputting an output pulse of the dropout detection means, and 3. The logic circuit according to claim 1, further comprising a logic circuit that forms and outputs the second dropout detection pulse based on an output pulse of a circuit and an output pulse of the mono-multi circuit. A variable speed reproduction signal processing circuit of the reproduction device. 4. A removing pulse forming means for forming and outputting a removing pulse for removing the pseudo pulse based on an output pulse of the dropout detecting means and an output pulse of the mono-multi circuit. And a second logic circuit that outputs the second dropout detection pulse based on an output pulse of the first logic circuit as the logic circuit and the removal pulse. 3. The variable speed reproduction signal processing circuit of the reproduction device according to 3 . 5. A removing pulse forming means for forming and outputting a removing pulse for removing the pseudo pulse based on an output pulse of the integrating circuit and an output pulse of the mono-multi circuit, 4. The apparatus according to claim 3 , further comprising: a second logic circuit that outputs the second dropout detection pulse based on an output pulse of the first logic circuit as the logic circuit and the removal pulse. A variable-speed reproduction signal processing circuit of the reproduction apparatus described above. 6. The variable-speed reproduction signal processing circuit according to claim 4, wherein said removal pulse forming means is constituted by a D-type flip-flop.