JPS6331380A - Magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To record pictures of high quality without damaging the audio signal of an already recorded video signal by recording the audio signal of a video signal to be recorded after in two frequency modulation recording channels by time control. CONSTITUTION:An input audio signal is delayed in a delay circuit 4 by a time corresponding to one field, and the input audio signal and this delayed signal are allowed to pass audio signal processing circuits 2a and 2b and have frequencies modulated by frequency modulating circuits 3a and 3b and are synthesized in a synthesizing circuit 5, and the output is supplied to heads 8a and 8b through a switch circuit 7. Since the already recorded video signal is erased and damaged if the output is recorded as it is, a head switching signal is applied to a terminal 9 to control heads by the switch circuit 7 so that an FM-modulated audio signal is recorded only in a period corresponding to the field of the video signal to be recorded after, and the signal is recorded in deep layer channels on a tape for every other field.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a magnetic recording and reproducing device (hereinafter referred to as VTR).
In particular, it relates to the recording of an audio signal that accompanies a video signal to be recorded later in a VTR that is configured to practically preserve recorded information on an already recorded tape and record another video signal on the tape. It is.

[Conventional technology]

In general, when recording on a home VTR, when the VTR enters the recording mode, the magnetic tape is erased by a full-width erasing head, regardless of whether the tape has recorded edges or not. Then, the first field of the video signal is transferred to recording track A on the magnetic tape as head A trajectory by RAD A to one of the video tapes.
The second field of the video signal is recorded by the other video B on the track B adjacent to the recording track A as a trace of the head BtIt.

[Problem that the invention seeks to solve]

Incidentally, there are cases where it is desired to record another program while playing back and viewing an already recorded program, but it is impossible to accomplish this with a single conventional VTR.

Therefore, the present applicant has developed a VTR that is capable of recording another video signal on the already recorded tape while practically preserving the already recorded edge information. This VTR will be explained below with reference to FIGS. 4 to 8.

In FIG. 4, 21 is a video signal input terminal, 22 is a synchronization circuit having a maximum delay time of one field period, and a vertical synchronization signal of the input video signal and a VT
This is for matching with that of the reproduced video signal from R24. 23 connects the output of the synchronization circuit 22 to 1
A first switch circuit 24 records the output signal of the first switch 23 or reproduces a video signal on a tape; 25 outputs the output of the VTR section 24 in one field; 26 is a second switch circuit that switches and outputs the four external outputs of the VTRTR section and an output delayed by 1 field; 27 is a video signal output terminal; and 28 is a head switching signal.

FIG. 5 is a diagram showing the head arrangement in the rotating drum of the VTR, and in the figure, 29 is the rotating drum, 30.31
132 is a rotating erase head (flying erase head) having a head width that is approximately the same as the recording track width.
, 33 is a magnetic tape. Also, Fig. 6+a+~(C1
1 is a diagram showing how video signals are recorded on a magnetic tape, 35 and 36 are video tracks, and 34 is a recorded control signal.

Next, the operation will be explained according to the recording timing chart shown in FIG.

It is assumed that the VTR 24 is already loaded with a magnetic tape on which a video A signal is recorded. In this state, a new video B signal is input to the video input terminal 21, and when writing this video B signal onto a magnetic tape on which a video A signal has already been written, a full-width erase head is used to save the existing edge information. (not shown), the VTR is operated in playback mode. Therefore, the capstan servo and drum servo are controlled using the playback mode control method.
Since heads A and B have different azimuth angles, the track 35 recorded by head A is controlled to be played back by head A, and the track 36 recorded by head B is controlled to be played back by head B, and the outputs of these heads are , for example, in Figure 7 (
When the head switching signal shown in a) is at a high level, the head A signal is outputted, and when it is at a low level, the head B signal is outputted to the outside of the VTRTR section. During normal reproduction, a reproduced video signal as shown in FIG. 7(b) is obtained.

Input video signal that you want to record in this state (Figure 7 (C))
is input, the vertical synchronization signal of the reproduced video A signal and the vertical signal of the input video B signal generally do not match in timing. Therefore, for example, since the head switching signal has a certain relationship with the vertical synchronization signal, The input video B signal is delayed by the synchronization circuit 22 to match the timing with the reproduced video signal A (FIG. 7(d)).

The synchronization circuit 22 may be any video delay circuit whose delay time is variable, as long as it can be delayed by a maximum of one vertical synchronization period (referred to as one field period or IV period).

Next, in order to record this signal on the track recorded by head B, for example, the first switch circuit 23 extracts it only when the head switching signal is at a low level.
e)) By applying this signal to the head via a signal processing circuit for recording and a recording amplifier (not shown), it is possible to record a video signal from the point where head B starts tracing the track. can. in this case,
If the already recorded signal is left as it is, it will be overwritten and beat disturbance will occur. Therefore, in advance of this head B, the flying erase head 32 is made to trace only the track 36 where the head 8M remains, and the information on the track 36 is Erase only. At this time, if the head width of the erasing head 32 is too wide or too narrow compared to the track width, the track next to the video signal that has already been written may be erased or some data may remain unerased. So,
The head width of the flying erase head 32 needs to be approximately the same as the recording track width. The manner in which data is recorded on the tape in this manner is shown in FIG. 6 (bl), and the resulting state of tape recording is shown in the same figure (C1).

That is, according to this VTR, the information of the first field of the video A that has already been recorded is saved every other field, and the information of the newly input video B is stored between the recording tracks of the video A. (In this example, the information of the first field) will be recorded every other field.

Next, the operation during playback will be explained.

During playback, a video output f in which the playback outputs of the video A signal and the video B signal are lined up for each field as shown in FIG. 8 is obtained from the VTR 24. This signal f is directly guided to the second switch circuit 26, while the one field delay output g obtained by delaying it by a one field delay circuit 25 for a period of 1v is guided to the second switch circuit 26. It is controlled to select between the direct video output signal f from the VTR 24 and the signal g delayed by one field at a predetermined timing for each field by a head switching signal 28 based on vertical synchronization of the video signal for each period. For example, a switch control signal created based on the head switching signal 28 generates a complete one-frame video A signal in which the direct video A signal and the video A signal delayed by 1v are arranged alternately. Output. Here, since the video A signal is recorded with field skipping in the output signal f, the next field is supplemented with the signal g delayed by 1V as described above, and a complete one-frame video signal is output to the video output terminal 27. It can be taken out. At this time, if the switching timing is shifted by 180 degrees from the previous switching timing in the switch circuit 26, a complete one-frame video signal k consisting of a direct video signal and a delayed video B signal is obtained by the switch control signal j, and later You can view the recorded program.

By the way, when two video signals can be recorded on one magnetic tape as described above, the problem is where to record the audio signals accompanying those video signals without sacrificing their quality. . That is, since there is not much difference between the first field and the second field of the video signal, it is possible to record and reproduce with field skipping as described above, and compensate the video signal of one field with the signal of the other field. However, audio signals are not practical unless continuity is maintained, and cannot be considered in the same way as video signals.

The present invention has been made in view of the above problems, and is a magnetic recording device that can record audio signals of video signals to be recorded later in high quality without causing any damage to audio signals accompanying video signals that have already been recorded. The purpose is to obtain a playback device.

Here, as for the audio signal accompanying the video signal, in the general VHS system and β system, it is recorded on the audio track provided at the end of the tape, but in addition to recording on this audio track, There are those that record on a video track by frequency multiplexing with a video signal, and those that record on a frequency-modulated audio signal track using spatial multiplexing such as deep recording.

[Means for solving problems]

The magnetic recording/playback device according to the present invention records an audio signal to be recorded on one of two frequency modulation recording channels (tracks) provided for audio signal recording, and records the audio signal on one of the two frequency modulation recording channels (tracks) provided for audio signal recording. A signal delayed by one vertical synchronizing signal period (one field period) is recorded on the other channel (track).

[Effect]

In this invention, the audio signal accompanying a video signal that is field-skipped and is not recorded is recorded with a delay of one field period, thereby compensating for the audio signal that is lost during playback.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an audio signal recording system of a VTR according to an embodiment of the present invention. In the figure, 1 is an audio signal input terminal, 2a, 2b are audio signal processing circuits, 3a, 3
b is frequency modulation (FM
) circuit, 4 is a delay circuit that delays the input audio signal by one field period, 5 is a synthesis circuit that synthesizes two frequency modulation circuits, 6 is a recording amplifier for passing the current necessary for recording to the head, 7 is a switch circuit (recording period control means) for controlling the recording period of an audio signal accompanying a video signal to be recorded later; 8a and 9b are rotary audio heads exclusively for audio recording; 9 is a head switching signal input terminal It is.

FIG. 3 is a diagram showing an example of the recording frequency arrangement of the FM audio signal of a VTR. Two deep channels are provided for recording.

Next, the functions and effects will be explained according to the timing chart shown in FIG. Here, in this embodiment, a case will be described in which two channels for audio are formed by deep recording as described above.

An input audio signal as shown in FIG. 2 ta+ is applied to the audio input terminal l. Here, for convenience of explanation, numbers ■, ■, ■ are given for each vertical synchronization signal (for each field) of the video signal accompanying the input audio signal.

Add ■, ■, ■, -・-. This signal is converted to 1 by delay circuit 4.
The signal delayed by one field period becomes as shown in Figure 2), and ■ is located in the field period of ■ in the original signal, and ■ is located in the field period of ■, and so on. There are two signals that are shifted by one field. These two signals are input to audio signal processing circuits 2a and 2b, respectively, where they are subjected to emphasis and noise reduction encoding processing. The processed audio signals are then input to frequency modulation circuits 3a and 3b, where they are frequency modulated. At this time, as shown in FIG. 3, for example, the non-delayed audio signal is assigned to carrier f1, and the delayed audio signal is assigned to carrier f2. Note that this may be reversed. The FM modulated audio signals obtained in this way are synthesized by a synthesis circuit 5, current amplified by a recording amplifier 6, and then sent to the heads 13a, 3b via a switch circuit 7.
supply to.

By the way, this VTR needs to practically save recorded edge information, so if you record as is, either head 3a or 3b will trace the remaining video track for every other field in recording mode. The recorded edge video signal is erased and damaged. Therefore, the second
The switch circuit 7 applies a head switching signal as shown in FIG. Control with.

In this way, a signal as shown in FIG. 2 fdl is recorded in every other field in the deep channel on the tape.

Note that the audio signal accompanying the video signal at the recorded edge is recorded in a normal audio track at the end of the tape in accordance with a general standard.

During reproduction, as shown in the signal shown in Figure 2 (di), the signal reproduced from the first channel is delayed by one field period, and this is combined with the signal reproduced from the second channel. ,■,■.

Continuous audio signals are obtained as shown in (1), (2), and so on. The one-field period delay circuit required during playback has the same function as the delay circuit used during recording, and is not used for recording and playback at the same time.
By sharing these, it becomes possible to make the circuit configuration economical.

In the above embodiment, the switch is shown as being placed after the recording amplifier, but this position is not limited to this position due to the circuit configuration; for example, it can be used to stop frequency modulation or turn off the power to the recording amplifier. This may be realized by such a method.

Further, although the above embodiment has been explained using a VTR having an FM audio channel that is spatially multiplexed such as deep recording, the present invention can be similarly applied to a VTR that has an FM audio channel that is frequency multiplexed with a video signal. can.

〔Effect of the invention〕

As described above, according to the present invention, in a VTR that is capable of recording another video signal while storing the video signal of the recorded edge on the magnetic tape of the recorded edge, the video signal to be recorded later is Since the accompanying audio signal is recorded in two frequency modulated recording channels in a time-controlled manner, the audio signal of the recorded edge video signal recorded on the audio track provided at the edge of the tape is damaged. There is an effect that the audio signal after the above can be recorded with high quality without any trouble.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an audio recording circuit of a VTR according to an embodiment of the present invention, FIG. 2 is a timing chart for explaining its operation, and FIG. 3 is a recording frequency arrangement of an FM audio signal of the VTR. Figures 4 through 8 are diagrams showing an example, and are diagrams for explaining a VTR that the applicant has already developed. Figure 4 is a block diagram of the VTR, and Figure 5 shows the arrangement of the heads within its rotating drum. 6 is a diagram showing how a video signal is recorded on a magnetic tape in the VTR, FIG. 7 is a timing chart diagram for explaining the operation during recording, and FIG. 8 is a diagram showing the reproduction. FIG. 4 is a timing chart diagram for explaining the operation at the time. 2a, 2b... audio signal processing circuit, 3a. 3b...Frequency modulation circuit, 4...1 field period delay circuit, 5...Synthesizing circuit, 7...Switch circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) The video signal of the already recorded magnetic tape is practically stored while another video signal is recorded on every other recording track of the magnetic tape, and the video signal is frequency-multiplexed or deep-channeled. In a magnetic recording and reproducing apparatus provided with two channels for recording the audio signal by frequency modulating the audio signal and recording the recording channel, the audio signal accompanying the another video signal is frequency modulated and recorded. a first audio signal processing system that delays the audio signal accompanying the another video signal by one vertical synchronization signal period and transmits the delayed audio signal to the first FM modulated audio signal; a second audio signal processing system that frequency-modulates a carrier frequency different from the carrier frequency to produce a second FM modulated audio signal; and a synthesis circuit that synthesizes the output signals of the first and second audio signal processing systems. , recording period control means for recording the output signal of the combining circuit only during the field period in which the another video signal is recorded in response to the output of the combining circuit, and the recording period control means records the output signal of the combining circuit only during the field period in which the another video signal is recorded, and the non-delayed audio signal is used for recording the two audio signals. A magnetic recording and reproducing apparatus characterized in that one of the channels records the delayed audio signal on the other channel.