JPH0654964B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a helical scan type magnetic recording / reproducing apparatus for controlling the running of a magnetic tape by using a pilot signal recorded on a video signal track by being superimposed on the video signal. (Less than,
VTR), and more particularly to a device for performing joint shooting when a temporary stop is made during recording.

[Conventional technology]

FIG. 4 is a block diagram of a conventional joint photographing apparatus shown in the specification and drawings of Japanese Patent Application No. 59-278598.

In FIG. 4, (1) is a rotary magnetic head, and although only one is shown in the figure for convenience, it is usually provided with two. (2) is a video signal for performing FM modulation and other processing on the video signal input to the VTR during recording, and FM demodulation and other processing for the signal reproduced by the rotary magnetic head (1) during reproduction. A processing circuit (3) is provided with a plurality of pilot signals each having a different frequency in synchronization with the signal indicating the switching of the circuit magnetic head (1), for example, 4
This is a pilot signal generation circuit that sequentially and repeatedly generates various types of pilot signals F _{1 to} F ₄ , and this pilot signal is for performing tracking control. (4) is a switch provided at the output of the pilot signal generating circuit (3), (5) is for superimposing the pilot signal on the FM-modulated video signal which is the output of the video signal processing circuit (2) The adder, (6), is a recording / playback selector switch. Further, (7) is a pilot signal extraction circuit for extracting a pilot signal from the reproduction signal, (8) is a pilot for detecting the level of the reproduction pilot signal and determining whether or not the reproduction track is recorded with the pilot signal. A signal presence / absence determining circuit (10) is a magnetic tape running control circuit for controlling the capstan motor (11) so that the magnetic tape is fed in the forward or reverse direction and stopped. (12) is a system control circuit, which sends control signals to the changeover switch (6), the video signal processing circuit (2), the switch (4) and the magnetic tape running control circuit (10) to make this VTR. To control.

FIG. 7 is a diagram showing a specific configuration example of the pilot signal presence / absence determining circuit (8). In the figure, (13) is an input terminal, (14) is a detection circuit for envelope-detecting a reproduction pilot signal, (15) is the output of this detection circuit (14) and the DC power supply (1
A comparator that compares the potential of 6), and (17) is an output terminal.

FIG. 5 is a diagram showing a timing chart of the conventional device, and the operation will be described with reference to this timing chart.

During normal recording, the changeover switch (6) and the video signal processing circuit (2) are controlled to the recording mode by the control signal C from the system control circuit (12), and the switch (4) is controlled by the control signal B. A signal in which the pilot signal is superposed on the video signal which is turned on and FM-modulated is recorded on the magnetic tape by the rotary magnetic head (1).

At this time, the capstan motor (11) is controlled by the magnetic tape running control circuit (10) which receives the control signals E and F from the system control circuit (12), and the magnetic tape is fed at a constant speed in the forward direction.

When a pause command is given in such a state, the switch (4) is turned off for one track period in synchronization with the head switching signal A by the control signal B output from the system control circuit (12), and then the system control circuit. The switch (4) is switched by the control signal C of (12), and the recording of the video signal and pilot signal on the magnetic tape by the rotary magnetic head (1) is interrupted.

The state of the recording track at this time is shown in FIG. In the figure, (1
8) is a magnetic tape, and (19) is a video signal track. As is apparent from this figure, during normal recording, the video signal and the pilot signal are recorded on the video signal track (19), but if a pause command is given while the track T ₀ is being recorded, Due to the operation of the system control circuit 12 as described above, the pilot signal is not recorded on the next track T ₁ , only the video signal is recorded, and thereafter the recording is interrupted. Then, after the recording is interrupted, the system control circuit (1
By the control signals E and F from 2), the capstan motor (11) is temporarily stopped via the magnetic tape running control circuit (10),
Then, the magnetic tape (18) is reversed and transferred by a predetermined amount and then stopped.

Next, when a recording start command is input as shown in FIG. 5,
The magnetic tape running is started by the control signals E and F from the system control circuit 12, and the magnetic tape is transported in the forward direction.

At this time, the changeover switch (6) and the video signal processing circuit (2) are set to the reproduction mode by the control signal C from the system control circuit (12), and the pilot signal extraction circuit (9) to which the reproduction signal is input. In (), the reproduced pilot signal is extracted. Then, in the magnetic tape running control circuit (10), by using the reproduction pilot signal, the locus of the rotary magnetic head (1) drawn on the magnetic tape is recorded on the magnetic tape recorded before the temporary stop command is input. to match the recording pattern, and a pilot signal generating circuit (3) pilot signal and the pilot signal F ₁ to F ₄ rotary magnetic head (1) is recorded in the track being scanned is generated from F ₁ to F _The tape running is controlled by controlling the capstan motor (11) so that the frequencies of ₄ match. Here, the amount of reverse transfer of the magnetic tape when a temporary stop command is input is such that when the magnetic tape running control based on the replay pilot signal is performed after restarting the magnetic tape running, the control system is fully settled within this time. It is set to be possible.

The reproduction pilot signal extracted in the pilot signal extraction circuit (7) is input to the magnetic tape running control circuit (10) for tracking control as described above,
It is input to the pilot signal presence / absence determining circuit (8). That is,
The reproduction pilot signal is the input terminal (13) of this discrimination circuit (8).
After being detected, the detection circuit (14) performs envelope detection, and the comparator (15) compares it with a constant potential given by the DC power supply (16) so that the output of the detection circuit (14) is higher than the DC power supply (16) potential. When it is larger, the high level is output, and when it is smaller, the low level is output from the output terminal (17). Therefore, when the rotary magnetic head (1) is scanning the magnetic tape recorded as shown by the signal D in FIGS. 4 and 5, from the track on which the video signal and the pilot signal are recorded, A reproduction pilot signal of a constant level is obtained and a high level is output from the pilot signal presence / absence determining circuit (8), but the rotary magnetic head (1) records a track T ₁ on which only a video signal is recorded and no pilot signal is recorded. During scanning, the reproduced pilot signal is only the crosstalk from the adjacent track T _0, so the level thereof is significantly lowered, and the output of the pilot signal presence / absence determining circuit (8) becomes low level. The output D of the pilot signal presence / absence determining circuit (8) is input to the system control circuit (12).

In the system control circuit (12), when a signal D indicating that there is no pilot signal is input, in synchronization with the head switching signal A, the video signal and the pilot signal are transferred from the next track to the magnetic tape by the control signal C. Recording resumes.

[Problems to be solved by the invention]

The conventional VTR splicing device is configured as described above. Therefore, if the presence / absence of a pilot signal can be normally discriminated as shown in FIG. During subsequent tape sequential playback, the pilot signal could not be extracted due to problems such as contact between the magnetic tape and the magnetic head and transient response of the tape running control system. For example, the pilot signal was recorded as shown in Fig. 5 (D ¹ ). If it is determined that there is no pilot signal even in the existing track, recording starts from the next track as shown in (C ¹ ) of the figure, and a track of overwriting occurs, which is a problem.

The present invention has been made in order to solve the above problems, and an object of the present invention is to obtain a rotary head type magnetic recording / reproducing apparatus capable of performing joint photographing without causing overwriting tracks and non-recording tracks. .

[Means for solving problems]

The VTR joint-shooting device according to the present invention records only the video signal without recording the pilot signal on the track corresponding to the pilot signal of the predetermined specific frequency among the pilot signals based on the recording pause command. Recording pause means for rewinding and stopping the magnetic tape by a predetermined amount after the recording is finished, and tape running control for starting the running of the magnetic tape based on the recording start command and tracking the pilot signals sequentially reproduced. Means and
A means for detecting the presence / absence of a missing pilot signal and a track next to the track where the pilot signal is missing when a missing pilot signal is detected during a period corresponding to the timing of a specific pilot signal. And a joint photographing means for performing a recording operation from the track.

[Action]

In the present invention, since a specific frequency pilot signal is used to identify the last video track when recording is paused, the pilot signal of the pilot signal is By specifying the frequency, the identification condition becomes double, and the joint photographing accuracy is improved.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (1) is a rotary magnetic head. (2) is this VTR
An image signal processing circuit for FM-modulating or demodulating an image signal input to the above or an image signal reproduced by the head, (3) is synchronized with a signal indicating switching of the rotary magnetic head (1), respectively. This is a pilot signal generation circuit that sequentially and repeatedly generates a plurality of pilot signals having four different frequencies, for example, F ₁ , F ₂ , F ₃ , and F ₄ . (4) is a switch provided at the output of the pilot signal generating circuit (3), (5) is for superimposing the pilot signal on the FM-modulated video signal which is the output of the video signal processing circuit (2) The adder, (6), is a recording / playback selector switch. (7) is a pilot signal extraction circuit for extracting a pilot signal from the reproduction signal, (8) is the presence or absence of a pilot signal for detecting the level of the reproduction pilot signal and determining whether or not the reproduction track is recorded with the pilot signal Discrimination circuit, (9) is the pilot signal presence / absence discrimination circuit
FIG. 2 shows a specific example of a gate circuit that takes the logical product of the output of (8) and the control signal G that the pilot signal frequency from the pilot signal generating circuit (3) is, for example, F ₁ . (1
0) means that the magnetic tape can be fed in the forward or reverse direction,
A magnetic tape running control circuit that controls the capstan motor (11) to stop. (12) is a system control circuit, which is the video signal processing circuit (2), switch
(4), changeover switch (6) and magnetic tape running control circuit (10)
A control signal is sent to the VTR to control the VTR.

FIG. 3 is a diagram showing a timing chart of an embodiment of the present invention, and the operation will be described with reference to this timing chart.

During normal recording, the switch (6) and the video signal processing circuit (2) are controlled to the recording mode by the control signal C from the system control circuit (12) and the switch (4) is controlled by the control signal B.
Is turned on and a signal in which the pilot signal is superimposed on the FM-modulated video signal is recorded on the magnetic tape by the rotary magnetic head (1).

At this time, the magnetic tape running control circuit (10) which receives the control signals E and F from the system control circuit (12) controls the capstan motor (11) to feed the magnetic tape at a constant speed in the forward direction.

In this state, when a temporary stop command is given as shown in FIG. 3, the control signal B output from the system control circuit (12) turns off the pilot frequency for the period of F ₁ , and then the control signal C causes the changeover switch. (6) is switched and recording of the video signal and pilot signal on the magnetic tape by the rotating magnetic head (1) is interrupted. Then, the capstan motor (11) is temporarily stopped via the magnetic tape running control circuit (10) by the control signals E and F, and then reversely rotated,
The magnetic tape is reversely transported by a predetermined amount and then stopped.

Next, as shown in FIG. 3, when a recording start command is input, the magnetic tape running is started by the control signals E and F from the system control circuit (12) and the magnetic tape is transported in the forward direction.

At this time, the changeover switch (6) and the video signal processing circuit (2) are set to the reproduction mode by the control signal C from the system control circuit (12), and in the pilot signal extraction circuit (7) to which the reproduction signal is input. The reproduced pilot signal is extracted.

The reproduced pilot signal extracted by the pilot signal extraction circuit (7) is input to the magnetic tape running control circuit (10) for tracking control and also to the pilot signal presence / absence determination circuit (8). In the pilot signal presence / absence determining circuit (8), the pilot signal is subjected to envelope detection, the presence / absence of the pilot signal is determined according to its magnitude, and its output D ₁ is input to the gate circuit (9).

D ₁ indicating that there is no pilot signal in the gate circuit (9)
Is at a low level and the signal D indicating that the pilot signal frequency output from the pilot signal generating circuit (3) is F _{1 is} at a high level, the output D ₂ outputs a high level and the system control circuit (12 ).

In the system control circuit (12), when D ₂ becomes high level, the control signal C from the next track is synchronized with the head switching signal A.
The recording of the video signal and the pilot signal on the magnetic tape is restarted.

Therefore, as shown in Fig. 3 (D ₁ ), the pilot signal presence / absence determining circuit
Even if the output D ₁ of (8) erroneously outputs a low level like d as described above, the frequency of the pilot signal at that time is F ₃
Since the signal G is at the low level, the output D ₂ of the gate circuit (9) remains at the low level, and it is possible to prevent the failure of continuous shooting.

Although the fixed pilot signal frequency is set to F ₁ in the above embodiment, it may be set to F ₂ , F ₃ , and F ₄ . Further, in the above embodiment, the case where the pilot signal is used and fixed to one of the four frequencies has been described.
Even if fixed to one of the two, the same effect can be obtained.

〔The invention's effect〕

As described above, according to the present invention, by fixing the pilot signal frequency of the last track of the joint shot, and by making the identification of the last track only at the same time as the fixed pilot signal frequency, the probability of misidentification of the last track is reduced. There is an effect that a VTR capable of highly accurate joint shooting can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a VTR joint photographing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of a gate circuit, and FIG. 3 is a diagram showing the operation of the apparatus shown in FIG. FIG. 4 is a block diagram showing a conventional VTR splicing device, FIG. 5 is a timing chart showing the operation of the conventional device, and FIG. 6 is a recording pattern on a magnetic tape before a temporary stop during splicing. FIG. 7 is a circuit block diagram showing an example of a pilot signal presence / absence determining circuit. In the figure, (1) is a rotary head, (2) is a video signal processing circuit, (3) is a pilot signal generating circuit, (4) is a switch,
(5) is an adder, (6) is a changeover switch, (7) is a pilot signal extraction circuit, (8) is a pilot signal presence determination circuit, (9) is a gate circuit, (10) is a magnetic tape running control circuit, (11) is a capstan motor, and (12) is a system control circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (5)

[Claims] 1. A rotary head is used to superimpose a plurality of tracking pilot signals having different frequencies and generated at a predetermined timing so that the frequencies of the adjacent tracks on the magnetic tape are sequentially different. The recording means for recording on the track, and based on the recording pause command, only the video signal is recorded without recording the pilot signal on the track corresponding to the pilot signal of the predetermined specific frequency among the pilot signals. After the recording is finished, the recording is stopped, and the magnetic tape is rewound from the track where the recording is finished by a predetermined amount to stop the magnetic tape, and the magnetic tape starts to run from the track based on the recording start command. A tape running control means for tracking the running of the magnetic tape by a pilot signal that is sequentially reproduced; A detecting means for detecting the presence or absence of a missing pilot signal that is sequentially reproduced, and a pilot signal when the missing of the pilot signal is detected by the detecting means during a period corresponding to the timing of the pilot signal of the predetermined specific frequency. A magnetic recording / reproducing apparatus comprising: a connection photographing means for operating the recording means from a track next to a track where a signal is lost. 2. The recording means has a video signal processing circuit for FM-modulating an input signal to convert it into a video signal suitable for recording on a magnetic tape, and a frequency different from each other in synchronization with switching signals of a plurality of rotary heads. A pilot signal generating circuit for cyclically generating a plurality of pilot signals, an adder for adding the video signal and the pilot signal, and an output signal of the adder is sequentially adjacent to the running direction of the magnetic tape. The magnetic recording / reproducing apparatus according to claim 1, comprising a plurality of rotary heads for recording on a video track. 3. A recording suspension means turns off transmission of a pilot signal for one track period of a track corresponding to a specific pilot signal in synchronization with switching signals of a plurality of rotary heads based on a recording suspension command. The magnetic recording / reproducing apparatus according to claim 1, further comprising a first switch and a second switch for switching from recording to reproduction of the magnetic tape after the first switch is turned off. 4. The tape running control means controls the pilot signal extraction circuit reproduced from the magnetic tape and the frequency of the reproduced pilot signal to coincide with the frequency of the original pilot signal recorded on the basis of the recording start command. 4. The magnetic recording / reproducing apparatus according to claim 1 or 3, further comprising a magnetic tape running control circuit for performing tracking control of running of the magnetic tape rewound by a fixed amount. 5. The joint photographing means uses a logical product of an output signal from a detecting means for detecting the presence / absence of a missing pilot signal based on a recording start command and a specific pilot signal of the recorded original pilot signals. The magnetic recording / reproducing apparatus according to claim 1, further comprising a gate circuit for detecting a track in which no specific pilot signal is recorded.