JPH0531718Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a circuit for suppressing audio noise generated in the continuous shooting portion of a video tape recorder.

(b) Prior Art In order to eliminate the discontinuity of the playback screen that occurs during recording pauses, video tape recorders employ a continuous shooting mechanism to form a playback screen with inconspicuous seams.

For example, Japanese Patent Application Laid-Open No. 58-128045 discloses that when setting a recording pause, the duty ratio of the last recorded control signal is changed and the tape is rewound slightly, and when a control signal with a different duty ratio is detected when setting a recording pause release. Disclosed is a repeating circuit that resumes recording at . According to such a configuration, not only can a natural playback screen with inconspicuous seams be obtained during playback, but also it can be used for cueing if a change in duty is detected.

(c) Problems to be solved by the invention However, in the above configuration, the seams in the playback screen are not noticeable, but the seams in the playback sound are noticeable, and the seams generate unpleasant noises.

(d) Means for Solving the Problems Therefore, in view of the above points, the present invention provides a control signal recording circuit that records control signals with different duty ratios before and after a seam, and a control signal recording circuit that detects the duty ratio of a playback control signal. fade-in of the reproduced audio signal. They are characterized in that they are each equipped with an audio level control circuit that controls fade-out.

(e) Effect Therefore, according to the present invention, the recording control signal is set to the first duty ratio in conjunction with the recording pause setting during recording, and the recording control signal is set to the first duty ratio in conjunction with the recording pause setting. By setting the second duty ratio for a certain period of time, control tracks with different duty ratios are gradually formed before and after the seam. Therefore, during playback, a control track portion with a different duty ratio that precedes the joint is played back to fade out the playback audio signal, and a subsequent control track portion is played back to fade in.

(F) Embodiment The present invention will be described below with reference to an illustrative embodiment.

In this embodiment, as schematically illustrated in FIG.
A normal control signal with a duty ratio of 60% is recorded in recording mode, and the duty ratio is increased to 80% (first duty ratio) in conjunction with the recording pause setting operation.
The control signal is recorded for 35 frames, recording is interrupted, and the tape is rewound by 30 frames to enter recording pause mode. Next, when you set the recording pause release setting, tape running will start and 25 frames will be recorded.
It enters the playback state in order to match the tape running phase with the newly recorded video signal. When the reproduction of 25 frames is completed, recording is restarted and a control signal with a duty ratio of 27.5% (second duty ratio) is recorded for about 30 frames. Then duty ratio 60
% original control signal is recorded. Therefore, the control track of the recording tape has a 30-frame section with a duty ratio of 80% (first area) and a 30-frame section with a duty ratio of 27.5% (second area) with the seam as the boundary.
will be formed.

FIG. 2 shows a circuit block diagram of this embodiment.
First, a recorded video signal is input to the vertical synchronization separation circuit 1 in the recording mode. The synchronously separated vertical synchronizing pulse is frequency-divided by 1/2 in a flip-flop circuit 2 and input to a duty setting circuit 3. This duty setting circuit 3 derives a pulse with a duty cycle of 60% in a normal state in which no control output is input, and this pulse is applied to the first RP switch 10.
The signal is supplied to the control head (CH) via the control head (CH) to form a control track.

In such a state, when it becomes necessary to set a recording pause for a commercial cut or the like, the normally open pause switch 19 is closed. Due to this closed circuit, the pause setting circuit 6 issues a pause setting output. This pause setting output is input to the duty control circuit 7 to produce a first control output, which changes the duty ratio of the output of the duty setting circuit 3 to 80% and puts the 35 frame counter 4 into a counting state. Therefore, when 35 control signals with a duty ratio of 80% are recorded, the count-up output of the 35 frame counter 4 is input to the duty control circuit 7, which deactivates the first control output. In conjunction with this de-energization, the recording control circuit 9 issues a recording interrupt output to deactivate the recording circuit (not shown) and switch the first and second RP switches 10 and 15.
is switched to the playback side, the duty setting circuit 3 cancels the duty ratio change, and the 35 frame counter 4
The counting ends, and the tape running control circuit 8 deactivates the normal rotation output to stop tape running. Therefore, tape running and recording operations are interrupted. Immediately thereafter, the tape running control circuit 8 issues a reverse output to cause the tape to run in the reverse direction. A 30 frame counter 12 inputting the reverse output counts 30 control signals obtained from the control amplifier 13. When the tape is rewound by 30 frames and a count-up output is derived from the 30 frame counter 12, the tape running control circuit 8 deactivates the reverse output, interrupts tape running, and enters a recording pause state.

Thereafter, when the pause switch 9 is reclosed due to the recording pause release setting, the pause setting circuit 6 inputs the pause release setting output to the duty control circuit 7, the tape running control circuit 8, and the 25 frame counter 11. The tape running control circuit 8 outputs a normal rotation output to cause the tape to run in the forward direction, and the capstan servo compares the output of the tracking circuit 14 with the output of the flip-flop 2 to match the running phase of the tape with the recording video signal. At the same time, the reproduction control signal is input to the 25 frame counter 11, and the VTR enters the reproduction state for 25 frames. When the count-up output of the 25 frame counter 11 is input to the recording control circuit 9, the recording circuit (not shown) is activated, the first and second RP switches 10 and 15 are switched to the recording side, and recording is resumed. Ru. At the same time, the duty setting circuit 7 issues a second control output to set the duty ratio of the duty setting circuit 3 to 27.5%. At the same time, the 30 frame counter 5 starts counting and inputs the count-up output to the duty control circuit 7 after 30 frames have elapsed. the result,
The second control output is turned off and the control signal is changed to 60% of its original value, resulting in a normal recording state.

When the tape recorded as described above is reproduced, the duty discrimination circuit 16, which identifies the duty ratio of the reproduction control signal, the fader control circuit 17, and the fader 18 are operated. A reproduction control signal reproduced from the control head (CH) is inputted to a duty discrimination circuit 16 via a control amplifier 13, and a reproduction audio signal reproduced from the audio head (AH) is derived via a fader 18. In such a reproducing state, when the duty discrimination circuit 16 detects a duty ratio of 80%, a fade-out output is input to the fader control circuit 17, and the fader control output gradually disables the fader 18.

Next, when the duty discrimination circuit detects a duty ratio of 27.5%, a fade-in output is input to the fader control circuit 17, and the fader control output gradually operates the fader 18. Therefore, the level of the reproduced audio signal is lowered before the continuous shooting portion and returned to the original level after the continuous shooting portion, thereby suppressing audio noise at the joint.

(g) Effects of the invention Therefore, according to the invention, no audio noise occurs in the continuous shooting portion, and the effect is great.

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention, with FIG. 1 being a diagram explaining the principle of operation, and FIG. 2 being a circuit block diagram. 16... Duty discrimination circuit, 18... Fader, 3... Duty setting circuit, 19... Pause switch.

Claims (1)

[Scope of Claim for Utility Model Registration] A video tape recorder having a repeating mechanism that interrupts recording and rewinds the tape in conjunction with the recording pause setting, and resumes recording continuously in the recorded area after the recording pause is set. The recording control signal is changed to the first duty ratio during the period after the recording pause is set and until the recording is interrupted,
a control signal recording circuit that changes the recording control signal to a second duty ratio for a certain period of time after resuming recording; An audio noise suppression circuit consisting of an audio level control circuit that detects the duty ratio and fades in the reproduced audio signal.