JPS6331381A - Magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To record another video information while leaving already recorded information as it is, by erasing information at every other video track of an already recorded tape with an erasing head and writing information to erased track parts. CONSTITUTION:An input video signal is delayed by a prescribed time in a synchronizing circuit 2 to match the timing to the reproduced video signal form a VTR 4, and the delay signal is taken out by a switching circuit 3 and is applied to a head B only when a head switching signal is in a low level. Since the beat disturbance is occurred by double writing if the already recorded signal is left as it is in this case, only information on the track which is the locus of a head B is erased by a flying erase head 12 in adance of the head B. Thus, already recorded information of video A is preserved in every other field, and the newly inputted information of video B is recorded in every other fields.

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, the present invention relates to a VTR for home use that is capable of recording additional video signals while practically storing previously recorded information on a pre-recorded edge tape.

[Conventional technology]

FIG. 6 Fa+ is a diagram showing the main parts of a home VTR described, for example, in "Home Video Technology" published by Japan Broadcasting Publishing Association, and shows a state in which a tape is being loaded. In the figure, 16 is a supply reel, 17 is a take-up reel, 9 is a rotating drum, 18 is a full-width erasing head,
19 is an audio/control head, and 13 is a magnetic tape.

The figure (bl is a diagram showing the arrangement of the video heads in the rotating drum 9, and in the figure, 10 and 11 are video hands A and video heads B attached at opposite positions with an angular interval of 180 degrees. , (C) schematically shows how a video signal is recorded on a magnetic tape.

Next, the operation will be explained.

The magnetic tape is pulled out from the cassette by the tape loading mechanism of the VTR, and this magnetic tape 13 is transferred from the supply reel 16 to the full-width erasing head 18, through one revolution of the drum 9, through the audio erasing recording/playback/control head 19, through the capstan 20, to the take-up reel. It is wound up at 17. At this time, a video signal is recorded or reproduced on the tape 13 by the video head AQ[l and the video head Bζ11 of the rotating drum 9 shown in FIG.

Figure 6 (C1) shows how video signals are recorded on this magnetic tape.When the VTR enters the recording mode, first
Even if 3 is a tape on which some video signal 22 has already been recorded or a new tape on which nothing has been recorded, it is erased by the full-width erasing head 18 (2 in the figure).
1), and then by video head A the first field of the video signal is recorded on the magnetic tape 13 as the head A trajectory 23, and then by video head B the second field of the video signal is recorded by the head A trajectory 23. B trajectory 24
At this time, it is recorded on the magnetic tape 13 as
A control pulse 14 synchronized with recording by the head is simultaneously recorded on the lower end of the tape by an audio/control head 19.

[Problem that the invention seeks to solve]

By the way, if it were possible to record additional information on a magnetic tape while preserving the previously recorded information, it would be extremely convenient for users and would also be effective when considering the economical efficiency of tapes. In the conventional VTR configured as described above, when the recording mode is set, the full-width erasing head operates and erases all the TRR information of the video signal at the recorded edge, making it impossible to leave any recorded information.

This invention has been made in view of the above, and allows a single VTR to use a tape that has already been recorded and record another video signal onto the tape while practically preserving the recorded information. The purpose is to obtain a magnetic recording/playback device.

[Means for solving problems]

The magnetic recording and reproducing apparatus according to the present invention includes a synchronization circuit that synchronizes a vertical synchronizing signal of an input video signal with a vertical synchronizing signal of a reproduced video signal of an edge recorded on a magnetic tape, and In addition to providing a switch circuit for taking out the video signal, a flying erase head (rotating erase head) having a head width that is approximately the same as the track width and for erasing only the track on which the input video signal is recorded is provided in the rotating drum. It is something.

[Effect]

In this invention, every other video track of a previously recorded tape is erased using a flying erase head, and another video signal time-synchronized to the erased track portion is written every other field. i
To record other video information while leaving the existing information.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a VTR according to an embodiment of the present invention. In the figure, 1 is a video signal input terminal, 2 is a synchronization circuit having a delay time of one field period at maximum, and a high-power video signal input terminal. vertical synchronization signal and V
This is for matching with that of the reproduced video signal from TR4. 3 is a first switch circuit that takes out the output of the synchronization circuit 2 every other field; 4 is the first switch circuit;
A VTR unit records the output signal of the switch circuit 3 or reproduces the video signal on the tape; 5 is a one-field delay circuit that delays the output of the tiVTR unit 4 by one field period; 6 is the output of the VTR unit 4; 7 is a video signal output terminal, and 28 is a head switching signal.

FIG. 2 is a diagram showing the arrangement of heads in the rotating drum of the VTR. In the figure, 9 is the rotating drum, 10.11 is a video head A and a video head B provided opposite each other, and 12 is a recording track. A rotating erase head (flying erase head) having a head width that is approximately the same as the width, 13
is magnetic tape. FIGS. 3+al to 3(C) are diagrams showing how video signals are recorded on a magnetic tape, with reference numerals 23 and 24 indicating video tracks and 14 indicating recorded control signals.

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

It is assumed that the VTR 4 has already been loaded with a magnetic tape on which a video A signal has been recorded. In this state, a new video B signal input is input to video input terminal 1, and this video B signal input is input to video input terminal 1.
When writing a signal to a magnetic tape on which a video A signal has already been written, the VTR is operated in playback mode so that the full-width erase head (not shown) is not operated in order to preserve the previously recorded information. Therefore, the capstan servo and drum servo are controlled using the playback mode control method. Here, since heads A and B have different azimuth angles, the track 23 recorded by head A is controlled to be played back by head A, and the track 24 recorded by head B is played back by head B. For example, the head output of
When the head switching signal shown in is high level, the signal of head A is V, and when it is low level, the signal of head B is V.
The signal is controlled to be output from the TR section 4. During normal reproduction, a reproduced video signal as shown in FIG. 4(b) is obtained.

Input video B signal to be recorded in this state (Figure 4 (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. For example, since the head switching signal has a certain relationship with the vertical synchronizing signal, the large video B signal is delayed by a predetermined time in the synchronization circuit 2 based on this signal to match the timing with the reproduced video signal (Fig. 4(d)
)). The synchronization circuit 2 may be any video delay circuit whose delay time is variable, and may be one that can provide a maximum of one vertical synchronization period (referred to as one field period or one period)'a.

Next, in order to record this signal on the track recorded in, for example, head B, it is extracted by the first switch circuit 3 only when the head switching signal is at a low level (FIG. 4(e)). By applying this signal to head B via a signal processing circuit for recording and a recording amplifier (not shown), a video signal can be recorded from the point where head B just begins tracing the track. In this case, if the already recorded signal is left as it is, overwriting will occur and beat disturbance will occur, so the flying erase head 12 is made to trace only the track 24 of the hend B locus in advance of this head B, and Delete only the information. At this time, if you go to a flying erase, 7 do 1
If the head width of 2 is too wide or too narrow compared to the track width, the track next to the video signal that has already been written will be erased, or some parts will remain unerased, so the flying erase head The head width of No. 12 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 FIGS. 3-), 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 of the recorded edge is saved every other field, and the information of the newly input video B ( In this example, the information in the first field) is recorded every other field.

Next, the operation during playback will be explained.

During playback, as shown in Figure 5, the video A signal and the video B signal are
Video output f in which the reciprocal output of the signal is arranged for each field
is obtained from the VTR4. This signal f is directly guided to the second switch circuit 6, while the one field delay circuit 5
A 1-field delay output g delayed by 1v period is guided to the second switch circuit 6. Further, the switch circuit 6 selects the direct video output signal f from the VTR 4 and the signal g delayed by one field at a predetermined timing for each field by a head switching signal 8 based on vertical synchronization of the video signal every IV period. For example, by using a switch control signal created based on the head switching signal 8, a complete one-frame video AfB signal in which a direct video A signal and a delayed video A signal are arranged alternately is generated. Output. Here, since the video A signal is recorded by field skipping in the output signal f, the next field is supplemented with the signal g delayed by 1 as described above, and a complete one-frame video signal is created at the video output terminal 7. 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 6, a complete one-frame video B signal k consisting of the direct video B signal and the delayed video B signal can be obtained by the switch control signal j. , you can view the recorded program later.

In this way, in this embodiment, it is possible to record a new video signal while preserving the information of the recorded edge for each field on the already recorded magnetic tape, so two programs can be recorded on one tape. When recording, it is possible to select and reproduce either the previously recorded information or the information recorded later, which is very convenient in actual use.

In the above embodiment, the switch circuit for recording is placed immediately after the synchronization circuit, but in this case, the switch output signal is an intermittent signal, so the subsequent circuits are not used for recording signal processing. There may be problems.

Therefore, in such a case, a switch may be provided just before recording on the tape, and the switch may be changed at this point.

〔Effect of the invention〕

As described above, according to the present invention, when recording an input video signal, the video signal is recorded every other field (every other recording track), and only the recording track is rotated and erased before the recording head. Since data is erased by the head, it is possible to record new video signals while practically preserving the recorded edge information on the magnetic tape that has already been recorded, and it is also possible to record a new video signal while using a field skip signal during playback. A complete desired one-frame video signal is created from the signal and a signal delayed by one field, and this is played back. Therefore, the video information that was already recorded and the video information that was written later can be combined. You can also select and view video information on a tape that has already been recorded, and if you suddenly want to record new video information while playing back and watching, you can also write new video information at the same time. It has the effect of being able to be saved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a VTR according to an embodiment of the present invention, FIG. 2 is a diagram showing the head arrangement in the rotating drum of the VTR, and FIG. 3 fat to tc+ are on the magnetic tape of the VTR. 4 is a timing chart for explaining the recording operation of the VTR, FIG. 5 is a timing chart for explaining the reproduction operation, and FIG. 6 is a diagram showing the recording state. A diagram showing the main part configuration of the conventional device, FIG. 6(b) is a diagram showing the head arrangement, and FIG. 6(C)
FIG. 2 is a diagram for explaining the recording state of the conventional apparatus. 2... Synchronization circuit, 3... First switch circuit, 4... VTR section, 5... 1 field delay circuit,
6... Second switch circuit, 12... Rotating erase head (flying erase head). Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A magnetic recording/playback device that can practically store recorded information on a previously recorded magnetic tape while recording other information on the tape, has a delay time of a maximum of one field period, and has a maximum delay time of one field period, and A synchronization circuit for synchronizing the vertical synchronization of the signal with that of a previously recorded playback video signal, and a first switch for synchronizing the output signal of the synchronization circuit with the vertical synchronization signal of the playback video signal and taking out every other field. a magnetic recording/reproducing unit for recording the output signal of the first switch circuit; and a magnetic recording/reproducing unit provided in a rotating drum of the magnetic recording/reproducing unit, having a head width substantially equal to the recording track width, and having a head width substantially equal to the recording track width, a rotary erasing head for erasing previously recorded information on a track on which a signal is to be recorded; a delay circuit for delaying the reproduced output signal of the magnetic recording/reproducing section by one field period; and an output signal of the delay circuit and the reproduced output video signal. and a second switch circuit that alternately switches and outputs each field in synchronization with a vertical synchronization signal. (2) The rotary head performs an erasing operation when recording an input video signal, and the full-width erasing head is configured not to operate when the rotary head operates. The magnetic recording and reproducing device according to item 1.