JPS633510B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording and reproducing apparatus, and more particularly to a helical scan type recording and reproducing apparatus suitable for use in connecting video signals during editing.

Conventional recording and reproducing devices with editing functions use a pulse signal from a pulse generator attached to a rotating drum and an input video signal to align the phase of the reproduced video signal with the reference input video signal during editing. The phase of the vertical synchronization signal obtained by synchronously separating the signal is compared, and the error is fed back to the drum motor connected to the rotating drum. This conventional method uses pulse signals from a pulse generator attached to the rotating drum, so the same servo loop can be used during recording and playback.
Therefore, servo errors do not occur during editing, but there is a problem that even if the reproduced video signal has a phase difference due to tracking shift or wow/flutter, it cannot be detected. There were drawbacks such as discontinuity in time (phase) and distortion of the upper part of the screen.

In order to eliminate this drawback, a plurality of recording and reproducing heads arranged on a rotating drum are provided in place of the conventional pulse generator, and the video signals reproduced from these recording and reproducing heads are used to generate a standard input video signal. A method has been proposed to perform phase matching with However, in this method, since the video signal reproduced by the recording/playback head is used, it is possible to match the point at which the editing begins, that is, the cut-in, but there is a problem in that it is difficult to precisely match the point at which the editing ends, that is, the cut-out. This is because the recording/reproducing head cannot be used for reproduction during the editing section, so the reproduced video signal cannot be used. In addition, with this method, during the editing section, one signal for phase comparison for the servo must be switched from the video signal reproduced by the recording/playback head to the pulse signal generated by the pulse generator, so servo errors occur during switching. The disadvantage was that this caused the rotating drum to shake.

The present invention has been made in view of this problem, and it is an object of the present invention to provide a video tape recorder that can smoothly connect video signals during editing.

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 7.

In the present invention, as shown in FIGS. 1 and 2, an electromechanical transducer is provided in addition to an erasing head 4 and a recording/reproducing head 5 on the side of a rotating upper drum 2 connected to a drum motor 1 that faces a fixed lower drum 3. For example, a movable displacement reproducing head (hereinafter referred to as a bimorph head) 6 made of a bimorph element so as to be displaced in a predetermined direction is provided and brought into contact with the magnetic tape 7. 8 is a control track head. During the so-called normal recording or reproducing operation, the bimorph head 6 is positioned on the same track as the erasing head 4 and the recording/reproducing head 5 for each track of the magnetic tape 7, as shown in FIG. During editing, for example, when inserting a new image in the middle of an image recorded on a tape, the erase head 4 and recording/playback head 5 play back a track at least one field earlier, as shown by the broken line in FIG. is displaced so that The bimorph head 6, as shown in FIG. One end of the bimorph element 9 is fixed to the protrusion 12 protruding from the bimorph power terminal 1 with a screw 13.
By applying a voltage from 5 and 16, this bimorph element 9 is electrostrictively driven and displaced, so that the head chip 10 attached to its free end is displaced in a predetermined direction, for example, in a direction perpendicular to the track of the magnetic tape. has been made. The output of this bimorph head 6 is taken out from output terminals 17 and 18.

FIG. 5 shows a circuit configuration of an embodiment of the present invention, and parts corresponding to those in FIGS. 1 to 3 will be described with the same reference numerals. In FIG. 5, reference numeral 20 denotes an input terminal to which a video signal to be recorded or inserted is applied during recording or editing, and is an input terminal for the input video signal FM modulation circuit 2.
After being subjected to FM modulation at step 1, the signal is supplied to the recording/reproducing head 5 via the switch 22, and is recorded or inserted onto a magnetic tape that has been previously erased by the erasing head 4.

During recording, a vertical synchronization signal is sent to the vertical synchronization separation circuit 2 from the video signal applied to the input terminal 20.
3, and is supplied to the phase comparator circuit 25 via the switch 24, as well as to the rotating drum 2.
A pulse signal from the pick up head 26 that detects the rotation (Fig. 1) is supplied to the phase comparator circuit 25 via the delay circuit 27 and switch 28 for phase comparison, and the error is fed back to the drum motor 1 to determine the phase. A match is made.

On the other hand, when editing, for example when inserting, input terminal 2
The vertical synchronization signal is synchronously separated from the video signal applied to the video signal 0 by the vertical synchronization separation circuit 23, and is supplied to the phase comparator circuit 25 via the delay circuit 29 and switch 24, and the old information before erasing is sent to the erasing head 4 and It is reproduced by the bimorph head 6 which is at least one field ahead of the recording/playback head 5, demodulated by the FM demodulation circuit 30 and sent to the switch 31.
A vertical synchronization signal is synchronized and separated by a vertical synchronization separation circuit 32 from a video signal supplied via a video signal, and then supplied to a comparison phase circuit 25 via a delay circuit 33 and a switch 28 for phase comparison. The video signal is fed back to the motor 1, and the phases of the video signal previously recorded on the magnetic tape and the newly inserted video signal are matched.

In this insert mode, the bimorph head 6 is reproducing old information at least one field ahead of the erasing head 4 and the recording/playing head 5 as described above, so there is a time difference between the two heads, but this time difference is Vertical synchronization separation circuits 23 and 3
The vertical synchronizing signals synchronously separated in step 2 are delayed by delay circuits 29 and 33 for a predetermined period of time, for example, a time corresponding to the head deviation and the track edge deviation, and are corrected by matching the phases.

In addition, switching the position of the bimorph head 6 during normal operation of recording or playback and during editing operation is as follows.
For example, input terminals 41 and 42 of a bimorph control logic circuit (drive circuit) 40 schematically shown in FIG.
By applying a normal operation command signal and an editing operation command signal to the bimorph element 9, a bimorph control voltage is applied to the output terminal 43, for example, as shown in FIG. 7. During normal operation, these heads 4 are located on the same track as the erase head 4 and recording/playback head 5, but during editing operation, these heads 4
and is displaced to a track position at least one field ahead of 5. Further, a reproduction tracking error voltage is applied to the input terminal 44 of the bimorph control logic circuit 40, so that the bimorph control voltage can also be corrected using this voltage.

Returning to FIG. 5 again, during playback, the switch 22 is switched to the P side, and the signal played back from the recording/playback head 5 is demodulated by the FM demodulation circuit 43 to extract the video signal and sent to the output terminal 35. . At this time, the drum servo outputs a vertical synchronization signal, which is synchronized and separated by a vertical synchronization separation circuit 32 from a reproduced video signal obtained via a switch 31, to a delay circuit 3.
3 and the phase comparator circuit 25 via the switch 28.
supply to.

Further, during recording or editing, the video signal reproduced by the bimorph head 6 and demodulated by the FM demodulation circuit 30 may be taken out to the output terminal 36 for monitoring. In this case, the video signal to be recorded is delivered to the output terminal 36 during recording, and the old video signal to be replaced is delivered to the output terminal 36 during editing.

As described above, according to the present invention, the reproducing head is attached to the rotating drum via the bimorph so as to be displaced in a direction substantially equal to the rotation axis of the rotating drum, and the bimorph is electrostrictively driven by the drive circuit. Therefore, the same reproducing head can selectively scan the track being scanned by the recording head and the track preceding the track being scanned by the recording head. Therefore, when the present invention is used in a recording/playback device having an editing function, the video signal recorded by the recording head can be played back and monitored by the playback head during recording, and the video signal can be replaced by the playback head during editing. It is possible to reproduce an old video signal that is intended to be played back, ie, a video signal that was recorded on a track that preceded the track that the recording head was scanning. Also, during editing, the rotational phase of the rotating head is determined by playing back the old video signal before erasing and comparing the phase of the vertical sync signal of this video signal with the vertical sync signal of the new video signal to be edited and recorded. It can also be controlled.

[Brief explanation of the drawing]

FIGS. 1 to 3 are schematic diagrams showing the mounting arrangement of the main parts of the present invention, FIG. 4 is a sectional view showing the mounting structure of the main parts of the invention, and FIG. 5 is an embodiment of the invention. 6 and 7 are schematic diagrams for explaining the operation of FIG. 5, respectively. 1 is a drum motor, 2 is a rotating upper drum, 3 is a fixed lower drum, 4 is an erasing head, 5 is a recording/playback head,
6 is a movable displacement playback head (bimorph head);
21 is an FM modulation circuit, 23 and 32 are vertical synchronization separation circuits, 25 is a phase comparison circuit, 29 and 33 are delay circuits, 30 is an FM demodulation circuit, and 40 is a bimorph control logic circuit (drive circuit).

Claims (1)

[Scope of Claims] 1. In a helical scan type recording and reproducing device, the erasing head and the recording head are mounted on a rotating drum so that the recording head scans the same diagonal track after the erasing head scans, and the reproducing head is attached to the rotary drum via an electromechanical transducer so as to be displaced in a direction substantially equal to the rotation axis direction of the rotary drum, and the track being scanned by the recording head and the track being scanned by the recording head are A recording and reproducing apparatus characterized in that a drive circuit electrostrictively drives the electromechanical transducer so that the reproducing head can selectively scan a preceding track.