JP2517986B2 - VTR - Google Patents

Description

TECHNICAL FIELD The present invention relates to a VTR used for editing video signals and the like.

[Summary of the Invention] The present invention relates to a VTR, in which a framing servo used for editing or the like is turned on only during a recording pause period and a predetermined period at the time of joint recording, and is turned off during a subsequent recording period, thereby disturbing framing of an input video signal. This is to prevent a large disturbance of the servo caused by.

[Conventional technology]

When a new video signal is spliced and recorded on a tape that has already been recorded when editing a video signal, etc., an odd / even number is used at the splicing part between the previously recorded video signal and the newly recorded video signal. Framing servo is performed to maintain the continuity of the field and prevent the disturbance of the reproduced image.

That is, for example, in a two-head VTR of the helical scan type, the relationship between a pair of one and the other recording heads and the odd and even fields of the video signal is set in advance, and recording is always performed in accordance with this. When a new video signal is input, the odd / even fields of this video signal are discriminated, and the rotational phase servo of the rotary head drum is performed based on this result.

[Problems to be solved by the invention]

However, when recording is performed by the framing servo described above, if a reproduction signal from, for example, a master tape is used as a new video signal, the continuity of odd / even fields is disturbed due to damage of the tape or the like. Sometimes. Even when a broadcast wave is used as a new video signal, the continuity of the field may be disturbed due to switching of relay points or insertion of CM.

When the field continuity of such a recorded video signal is disturbed, when recording is performed by the framing servo described above, the drum servo enters the pull-in operation at the time of this disturbance, and in the worst case, Since the retraction is performed from a position 180 degrees apart, there is a possibility that the servo may be significantly disturbed over several tens of frames thereafter. For this reason, the signal recorded in such a state of servo disturbance cannot be reproduced well, and during this period, there is a risk that the video may be lost due to muting or the like.

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

[Means for solving problems]

The present invention discriminates between odd and even fields of an input video signal (terminal (1)) (flip-flop (14)),
VTR for performing a framing servo in which a pair of one and the other recording heads (3) and the odd-numbered and even-numbered fields have a predetermined relationship (frequency dividing circuit (7), NAND circuit (16))
In the above, the framing servo is performed only for the recording pause period and the predetermined period (terminal (17)) before the start of the recording of the joint recording, and the framing servo is turned off (the switch (15)) for the subsequent recording period. The VTR is characterized in that the above recording is performed.

[Action]

According to this, the framing servo is performed during the pause period and the predetermined period before the start of the recording of the joint recording to maintain the continuity of the field at the start of the recording, and the framing servo is turned off during the recording period. Even if the field continuity of the video signal to be recorded is disturbed, the drum servo or the like is not disturbed, and the video signal can always be recorded in good condition.

〔Example〕

In FIG. 1, (1) is a new video signal input terminal, and the signal from this terminal (1) is supplied to a video signal processing circuit (2) and converted into a predetermined video signal for recording. The recording signal is supplied to a pair of heads (3) provided on a rotating drum (not shown) to supply the tape (4).
Recorded in.

Further, the signal from the processing circuit (2) is the sync separation circuit (5).
To the vertical sync separation circuit (6) to separate the vertical sync signal. This vertical synchronizing signal is supplied to the frequency dividing circuit (7) to form a signal inverted for each field, and this signal is supplied to the phase comparator (φ) (8). Further, a signal from a pulse generator (PG) (9) provided on the rotary shaft of the rotary drum is supplied to a phase comparator (8) through a predetermined waveform shaping circuit (10), and this comparison output is supplied to a drive circuit (11). ) Is supplied to the drum motor (12) to perform drum servo so that every other vertical synchronization signal and the rotation phase of the rotating drum have a predetermined relationship.

Further, the signal from the separation circuit (5) is supplied to the data input terminal D of the flip-flop (14) through the half H killer circuit (13), and the signal from the separation circuit (6) is transmitted through the switch (15). It is supplied to the clock input terminal C of 14). As a result, from the Q output terminal of the flip-flop (14), for example, in the odd field where the vertical synchronizing signal is provided at the 3H of the equalization pulse period, at the high potential, at the even field where the vertical synchronizing signal is provided at the 3.5H. The field discriminating signal having a low potential is taken out.

Further, the discrimination signal and the signal from the waveform shaping circuit are supplied to the NAND circuit (16). As a result, the NAND circuit (16) forms a signal having a low potential only when the signal from the generator (9) is generated in an odd field, and this signal is supplied to the frequency dividing circuit (7) to be divided. The phase of the circular output is inverted.

Therefore, in this device, servo is performed so that the signal from the pulse generator (9) is generated in the even field during the period when the switch (15) is ON, and the pair of one and other recording heads are odd and even. The framing servo is performed so that the field has a predetermined relationship.

Further, in this device, a control signal is formed by a system control circuit (not shown) or the like during the pause period and a predetermined period before the start of the continuous recording, and this signal is supplied to the switch (15) through the terminal (17). The control is performed so that the switch (15) is turned on only during the period of the lever signal.

That is, for example, in so-called pre-roll insert recording, when performing the recording as shown in FIG. 2A, when the start point of the joint recording is instructed, the tape is rewound for 3 seconds as shown in FIG. 2B, From that point, the normal traveling mode is set, and the switch (15) is turned on as shown in FIG. 7C for the first one second, and the framing servo is performed. Recording is started from the starting point after 3 seconds, and the switch (15) is turned off at this time.

In the pause insert recording, when the recording is performed as shown in FIG. 3A, when the pause is instructed at the start point of the joint recording, the tape is required to start the transfer as shown in FIG. 3B. It is rewound and put in a pause state, during which framing servo is performed as shown in FIG. When the pause is released, recording is started after the tape transfer is started, and the framing servo is turned off at this time.

Thus, according to the above-described device, the framing servo is performed during the pause period and the predetermined period before the start of the continuous recording, so that the continuity of the field at the start of the recording is maintained and the framing servo is turned off during the recording period. As a result, even if the field continuity of the video signal to be recorded is disturbed, the drum servo or the like is not disturbed, and a good video signal can always be recorded.

In the above-mentioned device, the specific circuit configuration of the field discrimination signal formation and the framing servo may be a circuit configuration other than the above.

Also, in the above-mentioned apparatus, even during normal recording, the head and the field can be made to have a predetermined relationship by temporarily setting the pause state at the start and starting recording after the framing servo is pulled in, and thereafter the framing servo is turned off. As a result, the disturbance due to the discontinuity of the input signal can be prevented.

According to the present invention, the framing servo is performed in the pause period and the predetermined period before the start of the recording of the joint recording to maintain the continuity of the field at the start of the recording, and the framing servo is performed during the recording period. Even when the continuity of the field of the video signal to be recorded is disturbed by turning off, the drum servo or the like is not disturbed, and a good video signal can always be recorded.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, and FIGS. 2 and 3 are diagrams for explaining the same. (1) is an input terminal, (2) is a video signal processing circuit, (3)
Is a rotary head, (4) is a tape, (5) is a sync separation circuit, (6) is a vertical sync separation circuit, (7) is a frequency divider circuit,
(8) is a phase comparator, (9) is a pulse generator, (10) is a waveform shaping circuit, (11) is a motor drive circuit, (12) is a drum motor, (13) is a half H killer circuit, (14) ) Is a flip-flop, (15) is a switch, (16) is a NAND circuit, and (17) is a terminal.

Claims (1)

(57) [Claims] 1. A VTR in which odd-numbered and even-numbered fields of an input video signal are discriminated, and a framing servo is performed in which a pair of one and other recording heads and the odd-numbered and even-numbered fields have a predetermined relationship. The VTR is characterized in that the period during which the servo is performed is only a recording pause period and a predetermined period before the start of recording of the joint recording, and during the subsequent recording period, the above framing servo is turned off to perform the above recording.