JPS636982A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce noise in a recording system and a vertical jitter at the time of a still reproducing in a reproducing system by approximating the time difference between reproducing signals from first and third rotating heads to a vertical cycle. CONSTITUTION:The titled device is provided with the recording system 1 provided with a noise reducing circuit 3 including a 1 horizontal cycle delay circuit 4, the reproducing system 2, first and the second rotating heads Ha, Hb different in gap azimuth from each other and the third rotating head H'a having the same gap azimuth as the first rotating head Ha and disposed in the vicinity of the second rotating head Hb; at the time of the still reproduction, the first and the third rotating heads Ha, H'a are used to perform the reproduction. The 1 horizontal cycle delay circuit 4 is used in the reproducing system 2, one of the reproducing signals from the first and the third rotating heads Ha, H'a at the time of the still reproduction is delayed by the 1 horizontal cycle delay circuit 4 and the time difference between the reproducing signals from the first and the third rotating heads Ha, H'a is approximated to the vertical cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal recording and reproducing device commonly used and suitable for a VTR called 8 mm video.

[Summary of the invention]

The present invention uses a one-horizontal-period delay circuit of a noise reduction circuit including a one-horizontal-period delay circuit provided in the recording system also in the reproduction system, and uses the first and third noise reduction circuits of the same gap azimuth during still reproduction. One of the reproduction signals from the rotary head is delayed by a one horizontal period delay circuit, and the first and third signals are
By making the time difference between the playback signals from the rotary head close to the vertical period, the circuit structure is simple and inexpensive, and noise reduction in the recording system and vertical jitter during still playback in the playback system are reduced. It can be realized.

[Conventional technology]

In a VTR called 8mm video, in addition to first and second rotating heads (rotary magnetic heads) that are arranged at an angle of 180 degrees and have different gap azimuths, a first rotating head and a For the third rotation of the same gap azimuth, the same inclined trunk on the tape (WL magnetic tape) is installed near the second rotating head during still playback and slow playback. The images are scanned and played back alternately.

On the other hand, the recording system of such a VTR includes a noise reduction circuit (line crawling reduction circuit) including a horizontal period delay circuit.
is provided.

[Problem that the invention seeks to solve]

In such a VTR, as long as there is no influence of Kukostalk,
The third rotary head is brought as close as possible to the second rotary head so that the time difference between the reproduction signals from the first and third rotary heads is as close to the vertical period as possible. Because the diameter of the attached drum is relatively small,
The time difference between the replayed signals is shifted by several horizontal periods with respect to the vertical period.

The present invention addresses these issues and provides a video signal recording and reproducing device that has a simple circuit configuration, a low cost, and is capable of reducing noise in the recording system and reducing vertical jitter during still playback in the reproducing system. This is what I am trying to propose.

[Means for solving problems]

The present invention comprises a recording system (1) equipped with a noise reduction circuit (3) including a horizontal period delay circuit (4), a reproduction system (2),
First and second rotary heads Ha, Hb having different gap azimuths, and a third rotary head H' having the same gap azimuth as the first rotary head Ha and disposed near the second rotary head Hb. A video signal recording and reproducing apparatus having a video signal recording and reproducing apparatus which uses first and third rotary heads Ha and H'a during still reproduction.
The one-horizontal period delay circuit (4) is also used in the reproduction system (2), and the first and third rotating heads Ha,
One horizontal period delay circuit (4
) to the first and third rotations.
, H'a is made close to the vertical period.

[Effect]

According to the present invention, one of the reproduction signals from the first and third rotary heads Ha and H'a during still reproduction is delayed by the one horizontal period delay circuit (4),
The time difference between the reproduction signals from the rotary heads Ha and H'a is made close to the vertical period.

〔Example〕

Below, with reference to FIG. 1, an embodiment in which the present invention is applied to a VTR called 8 mm video will be described in detail.
Prior to that, the rotating head (rotating magnetic head) will be explained. In FIG. 2, Ha and Hb have different gap azimuths and are attached to the rotating drum RD of the tape guide drum device at an angle of 180 degrees. H/a is a third rotary head attached to the rotary drum RD having the same gap azimuth as the first rotary head Ha, and sufficiently close to the second rotary head Hb as long as there is no influence of Kukostalk. It is.

During normal recording and playback, the tilted tracks on the tape (magnetic tape) are alternately scanned at the first and second rotational speeds to record and play back video signals. Alternatively, during slow playback, the first and third rotary heads l(a % H'a) alternately scan the same inclined track to obtain a playback signal.

Next, an embodiment of the present invention will be described with reference to FIG. (1) shows a recording system, and (2) shows a reproduction system, respectively. (3) shows a common circuit for the recording system (1) and the reproducing system (2). First, this common circuit (3) will be explained.

(5) and (16) are the input terminal and output terminal, respectively, of this common circuit (3). (4) is this common circuit (3
), the IH delay circuit (4) will be explained first. The input signal from the input terminal (5) is supplied to the AM modulator (6), and the AM modulated signal obtained from this is sent to a delay line (glass delay line, CCD, digital memory, etc.) with a delay amount of IH-τ. )(7) and is delayed.

(8) is a changeover switch, which switches the output of the delay line (7) and AM modulator (6) supplied to the fixed contacts d and Z by the movable contact m, and sends the switching output to the AGC circuit (synchronous AGC circuit). circuit) (9). Furthermore, this AG
The C circuit (9) connects the first and third rotating heads Ha%
This is to equalize the levels of the reproduced signals of H'a to avoid flicker. This AGC circuit (9)
In this case, capacitors (17) and (18) having different capacitance values between the capacitor and the ground can be switched by a changeover switch (19). In addition, the movable contact m of the changeover switch (19) is grounded, and its fixed contact a%
a' is connected to capacitors (17) and (18). A
The output of the C, C circuit (9) is supplied to an AM detector (10) and detected, and the detected output is supplied to a low-pass filter (the amount of delay is τ) (11). Thus,
An IH delay circuit (4) is configured.

The output of this low-pass filter (11) is the synthesizer (I2
) as the subtraction input. On the other hand, input terminal (5)
The input signal from is fed to this combiner (12) as a summing input. Then, the synthesis output of the synthesizer (12) is transmitted through the limiter (13) and the variable attenuator (14).
It is fed as a subtraction input to another combiner (15). The input signal from the input terminal (5) is also supplied to this synthesizer (15) as an addition input. And this synthesizer (15
) is supplied to the output terminal (16).

Next, the recording system (1) will be explained. Input circuit (2
7) and is separated into a luminance signal and a chromaticity signal. The luminance signal is supplied to the input terminal (5) of the common circuit (3) through the recording side fixed contact r and the movable contact m of the recording/reproduction changeover switch SW. This common circuit (3) functions as a noise reduction circuit (line crawling reduction circuit) in the recording system (1). Furthermore, at the time of recording,
The movable contact m of the changeover switch (8) remains switched to the fixed contact d side, and the changeover switch (19)
The movable contact m remains switched to the fixed contact a' side. In this noise reduction circuit (3), a signal without line correlation is obtained on the output side of the synthesizer (12), and by passing this through the limiter (13), the noise component is extracted.
This is supplied to a combiner (15) and subtracted from the luminance signal from the input terminal (5), thereby reducing the noise component in the luminance signal.

Further, the chromaticity signal from the luminance/chromaticity separation circuit (27) is supplied to the chromaticity signal processing circuit (28), where it undergoes signal processing such as low frequency conversion, and then is sent to the synthesizer (29) as an addition input. Supplied. On the other hand, a luminance signal with reduced noise components from the noise reduction circuit (3) is supplied to the pre-emphasis circuit (31) through the movable contact m and the recording side fixed contact r of the recording/reproduction changeover switch SW2. This pre-emphasized luminance signal is sent to an FM modulator (30).
After being subjected to FM modulation, it is supplied to the synthesizer (29) as an addition input, where it is added to the chromaticity signal from the chromaticity signal processing circuit (2g), and then sent to the rotating magnetic head (through the recording amplifier (32)). 33) and are recorded on the magnetic tape so that inclined tracks are formed.

Next, the reproduction system will be explained. Rotating magnetic head (45
) is supplied to a bypass filter (47) and a low-pass filter (51) through a regenerative amplifier (46), and is frequency-separated into a subject F M fi J luminance signal and chromaticity signal, respectively. The FM modulated luminance signal from the bypass filter (47) is supplied to the FM demodulator (4th) and demodulated, and the obtained luminance signal is passed through the de-emphasis circuit (49) to the dropout compensation switch (50). is supplied to the normal side fixed contact n.

The movable contact m of the changeover switch (50) is connected to the input terminal (5) of the common circuit (3) through the reset-side fixed contact p and the movable contact m of the recording/reproduction changeover switch SW.

This common circuit (3) functions as a noise reduction circuit during playback, and its IH delay circuit (4) functions as a noise reduction circuit during still playback and slow playback.
It is also used as a memory at the time of dropout in order to reduce the deviation of the time difference of the reproduced signal of H'a from the vertical period.

The color signal from the low-pass filter (51) is supplied to a color signal processing circuit (52) and subjected to signal processing such as high frequency conversion, and then supplied to a synthesizer (55) as an addition input. Further, the output terminal (20) of the common circuit (3) is connected to the still and slow side fixed contact fp of the normal/still and slow playback changeover switch (53) and the dropout fixed terminal do of the dropout compensation changeover switch (50). Connected. The output terminal (16) of the common circuit (3) is the movable contact m and the playback side contact p of the recording/playback switch SW2.
It is connected to the normal side fixed contact np of the changeover switch (53) through the normal side fixed contact np. The output from the movable contact m of the changeover switch (53) is supplied as an addition input to the synthesizer (55) through a noise reduction circuit (54) for reducing edge noise. The output of this synthesizer (55) is then output to an output terminal (56).

However, during normal playback, the selector switch (8)
The movable contact m of the changeover switch (53) is switched to the fixed contact d, the movable contact m of the changeover switch (53) is switched to the fixed contact np,
The movable contact m of the changeover switch (50) is switched to the fixed contact n side. At this time, the common circuit (3) functions as a noise reduction circuit (line crawling reduction circuit).

Further, during still playback and slow playback, the movable contact m of the changeover switch (53) is switched to the fixed contact rp side, and the movable contact m of the changeover switch (50) is switched to the fixed contact n. At this time, the first and third rotary heads Ha and H'a alternately scan the same inclined track on the tape to reproduce the recorded signal. When the first rotary head Ha is regenerated, the movable contact m of the changeover switch (8) is switched to the fixed contact a side, and the movable contact m of the changeover switch (19) is switched to the fixed contact a side, During playback of the third rotary head H'a, the movable contact m of the changeover switch (8) is switched to the fixed contact Z side, and the movable contact m of the changeover switch (19) is switched to the fixed contact Z side.
is switched to the fixed contact a' side. In this way, it is possible to reduce the deviation of the time difference between the reproduction signals of the first and third rotary heads Ha, H'a from the vertical period.

In addition, at the time of drop/out, the movable contact m of the changeover switch (50) is switched to the fixed contact do side, and when it is live, the movable contact m of the changeover switch (8) is switched to the fixed contact d (although it remains switched to the Ill side). During still and slow playback, the movable contact m of the changeover switch (8) is switched between fixed contacts d and z for each field.Therefore, during still and slow playback, the movable contact m of the changeover switch (8) is switched between the fixed contacts d and z. Drop/7 dropout compensation is performed only when switched to d.

In addition, the delay line (7) in FIG. 1 is as shown in FIG.
It is composed of a delay line (7) and a changeover switch (7b) for switching the output of the delay device (7a), and its normal reproduction side fixed contact np is connected to the output side of the delay line (7), and the delay device (7cL) is connected to the output side of the delay line (7). Discontinuity in the horizontal synchronizing signal during still and slow playback can be avoided by connecting the output side of the switch to the fixed contact rp on the still and slow playback side and switching the movable contact m between these fixed contacts np and fp. can.

Alternatively, the angle between the second and third one-rotation heads Hb and H'3 may be set to NH-τ (where N is a positive integer). Note that if τ is small, there is no problem even if this is ignored.

The AM modulator (2) and AM detector (10) of the above-mentioned common circuit (3) may be an FM modulator and an FM demodulator, respectively.

〔Effect of the invention〕

According to the present invention described above, it is possible to reduce noise in the recording system and reduce vertical jitter during still reproduction in the reproduction system with a simple circuit configuration and low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a modified example of a circuit system according to an embodiment of the present invention. (1) is a recording system, (2) is a reproduction system, (3) is a common circuit (noise reduction circuit), and (4) is an LH delay circuit.

Claims (1)

[Scope of Claims] A recording system equipped with a noise reduction circuit including a one-horizontal period delay circuit, a reproduction system, first and second rotary heads having mutually different gap azimuths, and the first rotary head. and a third rotary head disposed near the second rotary head with the same gap azimuth, and the video signal is reproduced using the first and third rotary heads during still reproduction. In the recording and reproducing apparatus, the one horizontal period delay circuit is also used in the reproduction system, and one of the reproduction signals from the first and third rotary heads during still reproduction is delayed by the one horizontal period delay circuit, A video signal recording and reproducing apparatus characterized in that the time difference between the reproduction signals from the first and third rotary heads is made close to the vertical period.