JPS5992480A - Inserting and editing device for video tape recorder - Google Patents

Abstract

PURPOSE:To ensure stable recording and reproducing operations by providing the 2nd control head which can reproduce a control signal prior to the normal 1st control head and detecting the presence or absence of said control signal. CONSTITUTION:Switches 32 and 33 are first connected to the terminal P side, and a switch 40 is connected to the terminal R side. When a control signal exists, an APC operation is carried out with a vertical synchronizing signal sent from a synchronizing signal separating circuit 38 and a reproduced control signal supplied from a control head 20 used as a reference signal and a comparison signal respectively. The revolution of a capstan 18 is synchronized with the vertical synchronizing signal. In case no control signal exists, the switches 32 and 33 are changed to the terminal R from the terminal P by the output of a D flip-flop circuit 48. Thus a capstan servo circuit 22 has a constitution of connection equal to that of a normal record mode. This ensures the stable recording operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an insert editing device for insert editing in a video tape recorder (hereinafter referred to as VTR).

[Technical background of the invention]

In VTR tape editing, insert editing refers to replacing a certain section of a tape on which signals have been previously recorded with another signal. In this insert editing, generally only the video signal is recorded, and the control signal is not recorded. Further, the capstan servo during insert editing is applied so that the reproduced control signal and the vertical synchronization signal in the recording signal are aligned in phase.

[Problems with background technology]

By the way, the control signal is not necessarily recorded in the part where you want to record the signal by insert editing, and the control signal may be missing for some reason, or the video signal may not have been recorded there from the beginning. In some cases, control signals are not recorded at all. In this way, if there is no control signal in the part where you want to record the signal by insert editing,
When recording, the capstan servo as mentioned above does not work,
Tape running becomes unstable. Further, when playing back this insert-edited portion, stable playback operation cannot be performed because there is no control signal.

[Purpose of the invention]

This invention was made in order to cope with the above-mentioned circumstances, and it is possible to perform a stable recording operation even when there is no control signal in the part where the signal is to be recorded by insert editing, and at the same time, the control signal can be recorded at the same time. An object of the present invention is to provide an insert editing device for a video tape recorder that can perform a stable playback operation even during playback by being able to record.

[Summary of the invention]

This invention' provides a second control head capable of reproducing control signals prior to a normal first control head for recording and reproducing control signals,
The presence or absence of a control signal is detected from the playback output of this second control head, and if there is no control signal, the capstan servo circuit is caused to perform servo operation during recording, and the first control head is used to - The system is configured so that the signal is recorded.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a general tape pattern of a helical scan type VTR. In the figure, a video track 12, an audio track 13, and a control track 14 are formed on a tape 11. Conventional insert editing involves rewriting only a certain portion of a video track with a new signal. FIG. 2 shows a tape pattern with a non-recorded portion 15. When a signal is recorded by insert editing on the non-recorded portion 15 of the tape 11 having such a non-recorded portion 15, a stable recording operation cannot be performed because there is no control signal. That is, when recording a signal by insert editing, the capstan servo is applied so that the playback control signal and the vertical synchronization signal in the video signal to be recorded are in phase, as described above. Therefore, in the absence of a control signal, the capstan servo is not activated, stable tape running cannot be obtained, and accurate recording cannot be performed. In addition, in conventional insert editing, control signals are not recorded, so if inserting is performed on the unrecorded portion 15), there is no control signal, so accurate playback operations cannot be performed. I can't.

This invention detects when there is no control signal in the part to be inserted edited and sets the capstan servo to the capstan servo used during normal recording to ensure accurate recording operation. It is something.

At the same time, by recording a control signal, stable playback operation can be obtained during playback.

FIG. 3 is a schematic diagram of a general helical scan type VTR. When recording signals by insert editing, the tape 11 is pulled out from the supply reel 16, wound around a cylinder 17 equipped with a rotating head, and run by the capstan 18, as in normal recording! +14 and is wound up on the winding reel 19. 20 is a control head that records control signals and performs M generation. A conventional VTR has only one control head, and therefore cannot record and reproduce control signals at the same time.

In this invention, another control head 21 is provided along the running path of the tape 11 with a predetermined distance from the control head 20 in a direction opposite to the tape running direction. Then, when editing inserts, the control signal is played back by the control head 21 before the control head 20, and if the υ control signal is not played back by the control head 21, the capstan servo is set to the servo for normal recording. At the same time, it also performs a control signal recording operation.

Here, using the general configuration of a capstan servo circuit, we will set the same capstan servo as during normal recording, and the configuration and operation for recording control signals during insert editing, according to the control signal detection results. explain.

The capstan servo circuit 22 shown in FIG. It has two servo loops: a phase control loop (hereinafter referred to as APC loop). AFC loop is capstan motor 23
Frequency generation coil (hereinafter referred to as FG) that detects the 0 rotation frequency
(referred to as coil)24. Amplification circuit 25. Monostable multi-bi break 269 trapezoidal wave generation circuit 27, phase comparison circuit 2
8. Gate pulse forming circuit 299 Phase compensation circuit 30. It consists of a motor and a drive circuit 31. In addition to the above circuit, the APC loop also includes switches 32, 33 . Amplification circuit 34.
Monostable multivibrator 359 trapezoidal wave generation circuit 36° phase comparison circuit 37. Synchronous signal separation circuit 38. Reference oscillation circuit 39. Switch 40, 1/2 frequency divider circuit 41. It has an FG coil 42 that detects the rotation frequency of the capstan 18.

The AFC loop operates in the same way whether during recording or reproduction, and operates to keep the rotational frequency of the capstan motor 23 constant according to the detection output of the FG coil 24. In the APC loop, the reference signal and comparison signal for obtaining phase control information are switched to different signals during recording and during reproduction. That is, during recording, the switches 32, 33, 40 are connected to the terminal R side, the vertical synchronization signal output from the synchronization signal separation circuit 38 is used as a reference signal, the signal output from the FG coil 42 is used as a comparison signal,
A phase comparison circuit 37 compares the phases of the two.

According to the comparison result, the rotational phase of the capstan motor 23 is controlled to be synchronized with the vertical synchronization signal.

As a result, the rotational phase of the cab stuff 180 is synchronized with the vertical synchronization signal, and stable operation is performed. The control signal is generated by supplying a signal output from the synchronizing signal separation circuit 38 to the control head 20 via the switch 32 and the switch 11.
recorded in

In Ichiriki and Kasei 11 yen, the switches 32, 33, and 40 are connected to the terminal P4n'l, and the oscillation number 44 from the reference oscillation circuit 39 is used as the signal, and the control hekudo 20
The reproduction control signal from 44-'j3i is compared, and the phase comparison circuit 37 compares the phases of the two. According to this comparative conclusion, the rotational phase of the capstan mork 23 is determined by the above-mentioned: l'! , ; Controlled in synchronization with the 4 signals. As a result, the rotational position fi of the capstan 18
'12 is synchronized with the vertical synchronization signal, and stable 11 raw operation is performed.

It should be noted that since the two consecutive capstan servo circuits 22 are common, a detailed explanation will be omitted here.

Next, the formation and operation of q, which are the characteristics of this invention, will be explained.

The reproduction output of the control head 21 is fed to an amplifier circuit 43. The output of this amplifier circuit 43 is supplied to one input terminal of an exclusive OR circuit 44, and
Fang jt circuit 4 consisting of resistor R11 + capacitor C1l
5 to the other input terminal of the exclusive OR circuit 44. 46 is an oscillation circuit whose oscillation signal is 1
It is supplied to the clock input terminal of the hexadecimal counter 47. The output of this hexadecimal counter 47 is supplied to a clock input terminal of a D flip-flop circuit 48. This D
A positive voltage is always applied to the D input terminal of the flip-flop circuit 48. The output of the exclusive OR circuit 44 is supplied to the reset terminal of the hexadecimal counter 47, and the signal obtained by delaying the output of the exclusive OR circuit 44 by the delay circuit 49 is supplied to the reset terminal of the D flip-flop circuit 48.

The operation during insert editing in the above configuration will be explained.

The switches 32 and 33 are initially connected to the terminal P side, and the switch 40 is connected to the terminal R side. This connection is made because it is necessary to consider the case where a control signal is present in the portion immediately after No. y is recorded by insert editing. That is, by setting the connection as described above, when a control signal exists, the synchronization signal 9; the vertical direction 1111 signal in the flITh signal from the ig circuit 38 is used as a reference signal, and the control head 20 The playback control signal from AP is used as a comparison signal.
Cn operation is performed, and the rotation of the capstan 18 is synchronized with the vertical synchronization signal. As a result, a stable tape running condition can be obtained and accurate signal recording can be performed.

On the other hand, when there is no control signal, the switches 32 and 33 are switched from the terminal P side to the terminal R side by the output of the D flip-flop circuit 48. In addition,
The switch 40 is directly connected to the terminal R. As a result, the connection configuration of the capstan servo circuit 22 is the same as that during normal recording, and a stable recording operation is performed. Also, at this time, a vertical synchronizing signal is supplied to the control head 20, and the control signal is recorded.

The operation of switching the switches 32 and 33 from terminal P to terminal R is performed as follows. control head 21
) (During insert editing, the control signal is reproduced before the control head 20. This reproduction output is amplified by the amplifier circuit 43. The exclusive OR circuit 44 and the integration circuit 45 form a differentiating circuit, and the amplifier circuit 4
Noculus is output at the timing of the rise and fall of the control signal output from 3. Typically, the period of the control signal is 30Hz. therefore,
Therefore, if the above differential /-,6 pulses are not output for longer than 16y7 (ms), for example, 20 (ms) with a margin of about 20 cm, it is possible to determine that the control signal does not exist. can. The frequency of the excavation signal from the oscillation circuit 46 is 400 Hz, and this excavation signal is converted by the hexadecimal counter 47 into a signal with a frequency of 25 Hz. Since the D flip-flop circuit 48 is triggered by the rising edge of the output signal of the hexadecimal counter 47, it is set to the set state after hexadecimal counter=20 (ms). However, if a reset signal is input to the hexadecimal counter 47 again before that, it will not return to the set state. Therefore, control head 21
If a control signal is obtained, the D flip flow circuit 48 will not be set, but if a control signal is not obtained, it will be 20 ( ms) after which it is set to the set state. Further, when a control signal is obtained again after the set state is set, the D flip flow circuit 48 is reset again by a pulse obtained by passing a differential pulse obtained from this control signal through a delay circuit 49. When the D flip flow circuit 48 is in the reset state, the switches 32 and 33 are connected to the terminal P, and when in the set state, the switches 32 and 33 are connected to the terminal R. Therefore, the connections of the switches 32 and 33 can be switched depending on the presence or absence of the control signal, and even when no control signal is present, the capstan servo can be applied and the control signal can be recorded.

The reason why the delay circuit 49 is provided is as follows. That is, since the control heads 20 and 21 are separated, when a pulse is obtained from the exclusive OR circuit 44, if the D7 lip-flop circuit 48, which is in the set state, is immediately reset, a portion of the control signal will be missing. I end up. Therefore, the delay circuit 48 is provided so that when a differential pulse is obtained again, the D flip flow circuit 48 is reset after a certain period of time has elapsed from this time. The delay time of the delay circuit 48 is determined depending on the distance between the control heads 20 and 21 and the tape speed. For example, it is sufficient if the distance between the control heads 20 and 21 is 4'Mm and the tape speed is 4'Mm.

As detailed above, in this embodiment, the control head 2 is provided at a predetermined distance from the control head 20 for recording and reproducing control signals in the opposite direction to the tape running direction during insert editing. . During insert editing, it is fully detected whether the control signal is being reproduced from the control head 21, and if it is not being reproduced, the switches 32 and 33 are immediately switched to the terminal R side, and the capstan servo circuit 22 is used for normal recording. In addition to using the same 41 connections as in the previous example, a control signal is recorded from the control head 20 via a switch 32. Therefore, even if the control signal does not exist in the part where the signal is to be recorded by insert editing, the tape 11 can be made to run stably and accurate recording operation can be performed. Furthermore, since the control signal is recorded at the same time as the video signal, accurate playback operation can be performed during playback. In this case, since the presence or absence of a control signal is detected by the playback output of the control head 21, which is separate from the control head 20, when the part where no control signal is present comes to face the control head 20, the switch 32 .33 switching may have already been completed. Therefore, it is possible to eliminate the possibility that the capstan servo is not applied temporarily or that the control signal is missing.

Here, I will explain the general procedure for insert editing.
Prior to signal recording by insert editing, first, the position of the portion where the signal is recorded by insert editing is confirmed. This can be done by memorizing, for example, the count value of a counter provided in the VTR to notify the user of the playback position of the tape 11, etc. - In this case, remember the count values for both the position where you want to start recording and the position where you want to end recording. After confirming the part where the signal is to be recorded by insert editing in this manner, the tape 11 is played back again, and when the counter value reaches the above value, the video signal to be recorded is supplied to the rotary head. Thereby, the video signal can be accurately recorded in the portion where the signal is desired to be recorded by insert editing. The above count value is stored in the memory, and when the tape 11 is played back again, the video signal is supplied to the rotary head when the count value becomes equal to the count value stored in the memory. For example, the supply of video signals can be automated.

By the way, a control signal recorded or reproduced by the control head 20 is generally used as a counting clock for the counter. In such a configuration, if a control signal does not exist in a part where a signal is to be recorded by insert editing, the value of the counter does not change in this part during playback for the above-mentioned confirmation. On the other hand, when editing inserts, switch 32.33
is connected to the terminal R side, the counter counts the control signals supplied to the control head 20 for recording. Therefore, it becomes impossible to completely record the signal in the part where the signal is desired to be recorded.

FIG. 5 shows a circuit configured to eliminate this problem, in which a switch 51 is provided on the control signal supply line to the counter 50, and the D7 lip-flop circuit 4
8 is in the set state, the switch 51 is turned off. According to such a configuration, the counting operation of the counter 50 is stopped during a period when no control signal is present. Therefore, the counting operation of the color/recorder 50 is the same as that during playback, and a predetermined signal can be completely inserted into a portion where a predetermined signal is desired to be recorded. In FIG. 5, the same parts as in FIG. 4 are given the same reference numerals.

Further, the control head 2 can be provided within a control/sound head assembly 52, as shown in FIG. 6, for example. This control/sound head structure 5
2, as is well known, is an audio head 53. control head F
A 2'eEl voice erasing head 54 is integrally incorporated therein. In this case, if the control head 21 is provided below the audio erasing head 52, it is possible to secure a position separated from the control head 20 by a predetermined distance in the direction opposite to the tape running direction (arrow X direction in the figure). can.

Toxic power ≦ # Even if there is no control signal in the part where you want to record the signal due to insert editing, stable recording operation can be performed, and by being able to record the control signal at the same time as this operation, it is possible to record the control signal at the same time. It is also possible to provide an insert editing device for a video tape recorder which can also perform stable playback operations.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a general tape pattern of the helical scan method, FIG. 2 is a diagram showing a tape pattern having a non-recorded part, and FIG. 3 is an embodiment of an insert editing device for a video tape recorder according to the present invention. FIG. 4 is a circuit diagram showing the same circuit configuration; FIG. 5 is a circuit diagram showing the main parts of the second embodiment of the present invention; FIG. It is a front view which shows the principal part of the 3rd real family example of this invention. 11... Tape, 18... Capstan, 20°2
DESCRIPTION OF SYMBOLS 1... Control head, 22... Capstan servo circuit, 43... Amplifying circuit, 44... Exclusive OR circuit, 45... Integrating circuit, 46... Oscillation circuit, 47... Hexadecimal counter, 48...D flip-flop circuit, 49...Delay circuit, 50...Counter, 51...Switch, 52...Audio/control head structure, 53...Audio head, 54...
Sound erasure head.

Claims (4)

[Claims] (1) a first control head for recording and reproducing control signals; and a first control head disposed at a predetermined distance from the first control head in a direction opposite to the running direction of the tape during insert editing. A second control head that reproduces the control signal from the tape prior to the signal, and a reproduction output of the second control head, detects the presence or absence of the control signal, and if there is no control signal, at least the capstan servo. An insert editing device for a video tape recorder, comprising control signal detection means for causing a circuit to perform a servo operation during recording and for causing a control signal to be recorded on the tape by the first control head. (2) The control signal detection means includes a differentiating circuit that differentiates the playback output of the second control head, and has a count-up period longer than the differential pulse period of the control signal output from the differentiating circuit, and A counter to be reset, a D flip-flop circuit set to a set state by the count-up output of this counter, and a D flip-flop circuit that generates the differential pulse approximately required for the tape to move between the first and second control pads. This delayed pulse causes the D
2. The insert editing device for a video tape recorder according to claim 1, further comprising a delay circuit that resets the flip-flop circuit. (3) The positional information of the part where the signal is to be recorded is obtained by insert editing by counting control signals, and when there is no information roll signal such as the playback position of the tape, the counting operation of the counter is prohibited. An insert editing device for a video tape recorder according to claim 1. (4) Claims characterized in that the second control head is integrally formed with an audio/control head structure formed by integrally forming an audio head, an audio erasing head, and the first control head. 2. The insert editing device for a videotape recorder according to claim 1.