JP2629848B2 - Playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reproduction apparatus applied to, for example, a U-standard VTR.

[Summary of the Invention]

The present invention relates to a reproducing apparatus, which detects the presence or absence of a time code signal when a time code signal is recorded on a longitudinal track provided so as to overlap an end of an oblique track on which a video signal is recorded. Is corrected based on the video signal.

[Conventional technology]

In a so-called U-standard VTR, the recording of a time code signal used for editing or the like is performed such that a longitudinal track is at least partially overlapped with an end of a diagonal track where a video signal is recorded as shown in FIG. The recording is performed by deep recording on this track. In this case, the time code signal is a pulse train of 1.2 kHz and 2.4 kHz,
This signal is recorded at a tape speed of 9.53 cm / sec.

[Problems to be solved by the invention]

However, the time code signal recorded in this manner is also reproduced by the rotating head in the above-mentioned overlapping portion of the track. In that case, the relative speed of the rotary head is 10.26 m / sec, which is about 108 times the relative speed (= tape speed) of the longitudinal track. For this reason, the frequencies of the reproduced time code signal are 129 kHz and 258 kHz, and this signal is mixed as noise into the vertical synchronizing portion of the reproduced video signal, thereby causing various problems such as image quality deterioration.

On the other hand, the applicant of the present application has previously filed an application (Japanese Patent Application No. 62-13107) for detecting this noise and correcting the noise removal of the reproduced video signal based on the detected signal.

That is, FIG. 5 shows an outline of the apparatus. In the figure, (11a) and (11b) are rotary heads for reproducing video signals, and signals from the heads (11a) and (11b) are supplied to a reproduction amplifier (12a) respectively. ) (12b) and are combined by an adder (RF switch) (13) to form a continuous signal. The signal from the adder (13) is supplied to a high-pass filter (14) to extract an FM-modulated luminance signal component. This signal
Demodulated by FM demodulator (15), and low-pass filter (16),
The signal is supplied to a noise removal circuit (noise canceller) (18) through a trap circuit (17). The signal from this circuit (18) is supplied to a mixer (19).

The signal from the adder (13) is a low-pass filter (2
0), and the low-frequency converted color signal components are extracted. This signal is supplied to the frequency conversion circuit (23) through the mute circuit (21) and the ACC circuit (22), and is returned to the original band. The returned signal is supplied to the mixer (19) through the band pass filter (24).

As a result, the demodulated luminance signal and the color signal returned to the original band are mixed to form a video signal, which is taken out to the output terminal (25).

On the other hand, (26) is a fixed head for reproducing a time code signal, and a signal from this head (26) is taken out to a terminal (28) through a reproduction amplifier (27), and a time code reproduction circuit ( (Not shown).

In this device, the signal from the low-pass filter (20) is supplied again to the low-pass filter (41), and a band corresponding to the time code signal reproduced by the rotary heads (11a) and (11b) is extracted. This signal is supplied to a comparator (42), and a signal of a predetermined level or more is taken out.
The extracted signal is a monostable multivibrator (43)
And supplied as a continuous signal.

Further, for example, a signal from a low-pass filter (16) is supplied to a sync separation circuit (29) to generate a vertical blanking signal. Further, the blanking signal and the continuous signal from the above-described vibrator (43) are supplied to a monostable multivibrator (30) with a gate, and a control signal for a predetermined period from the rise of the blanking signal during a period in which the continuous signal exists is provided. The trap signal (17) is formed by this control signal.
And the mute circuit (21) is driven.

As a result, muting of the color signal mixed with the reproduction signal of the time code signal and removal of the noise component of the demodulated luminance signal caused by the mixing are performed.

However, this conventional device requires a low-pass filter (41) for detecting noise components and a monostable multivibrator (43) for signal continuity. May rise.

In addition, there is a possibility that erroneous detection may occur due to erroneous detection of VITS, RF switch switching pulses, and the like in the vertical blanking period, and there is a problem that the circuit scale is further increased in order to prevent this erroneous operation.

The present application has been made in view of such points.

[Means for solving the problem]

The present invention relates to a reproducing apparatus for reproducing a video signal recorded on an oblique track and a time code signal deeply recorded on a longitudinal track provided so as to at least partially overlap the end of the oblique track. A separation circuit (high-pass filter (14), low-pal filter (20)) for separating a luminance signal and a chrominance signal from the extracted video signal, and a mute circuit (21) for selectively outputting the chrominance signal based on a control signal And a trap circuit (17) for receiving the luminance signal and reducing the level of a signal component of a predetermined frequency based on the control signal, and a time for detecting the presence or absence of the time code signal and outputting a time code detection signal. A code signal detection circuit (integrator (1), comparator (2)), an extraction circuit (synchronization separation circuit (29)) for extracting a vertical synchronizing signal of the video signal, A playback device comprising a control signal forming circuit (monostable multivibrator (30)) for forming the control signal based on a vertical synchronization signal and the time code detection signal.

[Action]

According to this, by detecting the time code signal itself and forming the control signal, the possibility of malfunction is extremely small, and the circuit configuration therefor can be extremely simplified.

〔Example〕

FIG. 1 shows a configuration of an example of the apparatus, and portions corresponding to those of the prior art in the figure are denoted by the same reference numerals and description thereof is omitted.

In this figure, a time code signal taken out from an output terminal (28) is supplied to an integrator (1), and this integrated signal is supplied to a comparator (2). Output is taken. The comparison output is supplied to the monostable multivibrator (30), and a control signal for a predetermined period is formed from the rise of the vertical blanking signal from the sync separation circuit (29) during the period when the comparison output is present.
Then, the trap circuit (17) and the mute circuit (21) are driven by the control signal.

 Others are the same as in the prior art.

Therefore, in this apparatus, when a video signal as shown in FIG. 2A is being reproduced, a reproduced signal of a time code signal is superimposed on this reproduced signal as shown in FIG. 2B. On the other hand, when the time code signal is recorded, a signal of a logical level of "1" is taken out from the comparator (2) as shown in FIG. With the blanking signal, a control signal corresponding to the superposition period of the time code signal as shown in FIG. E is taken out from the monostable multivibrator (30).

The specific configuration of the multivibrator (30) is, for example, as shown in FIG. 3, the output of the comparator (2) is inverted and supplied to the OR circuit (31), and the vertical blanking signal is supplied to the OR circuit (31). , And this OR output is supplied to the T terminal of the T flip-flop (31). A power supply Vcc is supplied to the CP terminal, and a capacitor Cx and a resistor Rx for determining a time constant are connected between the T ₁ and T ₂ terminals. As a result, when the vertical blanking signal rises during the period in which the comparison output is present, a control signal is generated during the time constant period determined by the capacitor Cx and the resistor Rx, and the time code signal is adjusted by adjusting the time constant. Can be adjusted to the superimposition period of

This control signal is supplied to the trap circuit (1
7) and supplied to the mute circuit (21), the noise component is removed by reproducing the time code signal mixed in the reproduced video signal.

The noise component is removed in this way,
According to the above-described device, by detecting the time code signal itself and forming the control signal, the risk of malfunction is extremely small, and the circuit configuration therefor can be extremely simplified.

In the device described above, the integrator (1) and the comparator (2) are also used to obtain an indicator output (3) indicating that a time code signal is recorded, and generate the control signal. Only a monostable multivibrator (30) is provided exclusively.

Also, since the recording / reproducing head (26) for the time code signal to be recorded in the deep layer is provided prior to the rotary heads (11a) and (11b), there is a time margin from the detection of the time code signal to the start of reproduction by the rotary head. The operation can be reliably performed.

〔The invention's effect〕

According to the present invention, by detecting the time code signal itself and forming the control signal, the risk of malfunction is extremely small, and the circuit configuration therefor can be extremely simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of the present invention, FIGS. 2 and 3 are diagrams for explaining the same, and FIGS. 4 and 5 are diagrams for explaining the prior art. (1) is an integrator, (2) is a comparator, (11a) and (11b) are rotating heads, (14) is a high-pass filter, (15) is an FM demodulator, (17) is a trap circuit, and (20) is Low-pass filter, (21) mute circuit, (23) frequency conversion circuit,
(25) is an output terminal, (26) is a fixed head for time code reproduction, (29) is a sync separation circuit, and (30) is a monostable multivibrator.

Claims (1)

(57) [Claims] 1. A reproducing apparatus for reproducing a video signal recorded on an oblique track and a time code signal deeply recorded on a longitudinal track provided so as to at least partially overlap an end of the oblique track, A separation circuit that separates a luminance signal and a color signal from a reproduced video signal, a mute circuit that selectively outputs the color signal based on a control signal, and a luminance signal that is input, and a predetermined signal is input based on the control signal. A trap circuit for reducing the level of a frequency signal component, a time code signal detection circuit for detecting the presence or absence of the time code signal and outputting a time code detection signal, and an extraction circuit for extracting a vertical synchronization signal of the video signal A control signal forming circuit that forms the control signal based on the vertical synchronization signal and the time code detection signal. Reproducing apparatus and butterflies.