JPS63151280A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To make it possible to record/record video signals in plural channels by changing the number of revolution of a drum and time base compression at the time of recording so that all the video signals in plural channels are recorded on a tape, and executing the time base elongating only a desired video signal component at the time of reproducing. CONSTITUTION:In a field memory (b) 22, only, the odd-number fields of the second video signals are written. A vertical synchronizing signal 10 whose time base is 1/2-compressed are read with a clock whose rate is double that for reading. In the result, the time base compressed signal is obtained in an output 24. At the time of reproducing, a signal detected by a magnetic head 31 is amplified by a reproduction amplifier 33, and lead to the P-side of a switch 14. A vertical synchronizing signal is frequency divided by half in a memory control circuit (B) 17 to generate pulse signals. The generated signal is made a write signal for writing in a memory to determine which of a first video signal or a second video signal should be selected and reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus (hereinafter referred to as a VTR), and particularly to an apparatus capable of recording and reproducing a plurality of different video signals.

BACKGROUND OF THE INVENTION All VTRs currently in practical use for home use are basically capable of recording and reproducing one channel. In order to record and play back multiple channels of video signals sent at the same time, it is necessary to use a number of VTRs corresponding to the number of channels, or to have multiple heads stacked on top of each other, which is not practical. do not have.

A multi-channel recording and reproducing apparatus for video signals is disclosed in, for example, Japanese Patent Laid-Open No. 179686/1986.

This is a VTR in which two heads with different azimuth angles are mounted on a rotating drum at 1800 degrees opposite positions, and each head alternately forms a track pattern on a running tape diagonally in the longitudinal direction of the tape to perform recording and playback. During recording, one video signal is used as a reference for head switching, and this video is recorded using only one head during the first half-rotation period of the drum, and another video signal is stored in memory and then transferred to the drum. The configuration is such that each video signal is read out during the second half-rotation period and supplied only to the other head, so that each video signal is recorded alternately on a predetermined trunk with the position of the vertical synchronization signal constant, and during playback, each video signal is read out and supplied only to the other head. One track length of the selected one of the two reproduced video signals derived from the head is stored in the memory again, and by switching and selecting the readout signal of this signal and the signal from the head Z, one video is generated. It is structured so that

Problem 5 to be Solved by the Invention Vane However, in the above configuration, the first video signal and the second video signal are alternately recorded on the inclined track formed at a rate of one per field. During playback, one field is interpolated with the signal of the previous field and played back, so when viewed on a monitor, the problem is that the screen becomes unpleasant with a lot of flicker compared to normal recorded and played back images. there were.

SUMMARY OF THE INVENTION In view of this, an object of the present invention is to provide a magnetic recording and reproducing apparatus that can record and reproduce video signals of multiple channels with image quality that is almost the same as that of normal recorded and reproduced images.

Means for Solving the Problems The magnetic recording and reproducing apparatus of the present invention provides that when a first video signal and a second video signal are given simultaneously, the first video signal and the second video signal are are written in the first and second memories, respectively, the first video signal is read out from the first memory with dedicated time axis compression at a predetermined timing, the second video signal is read out from the second memory, 6 bases read from the first memory.

The time axis is compressed and read out at a timing that matches the phase of the time axis compressed signal and the vertical synchronization signal, and both are switched at the timing of the time axis compressed vertical synchronization signal to form one continuous time axis compressed signal. Then, the video signal is recorded on a magnetic tape by a magnetic head attached to a rotating drum that rotates at a vertical synchronization period, and during playback, the first or second video signal component of the playback signal from the magnetic head is recorded. which one selects one and writes it to the first or second memory,
The readout is performed by expanding the time axis twice as much as when recording, so that the first reproduced video signal or the second reproduced video signal in a complete form with the time axis returned to its original state can be obtained. According to the above-described structure, the present invention compresses the time axis of the first and second video signals into one continuous signal, and rotates the rotary drum at a vertical synchronization period. Recording and playback is performed, and during playback, an arbitrarily selected first or second video signal component is expanded in the opposite direction to that during recording to obtain a playback video signal whose time axis is returned back. During the recording and playback process, the video signal is reproduced in its perfect form without losing any video information.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a block diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention, in which 1 is a first video signal input terminal, 2, 9.15 is a vertical synchronizing signal separation circuit, and 4
is memory control circuit A, 7 is field memo IJ
A, 11 is a dedicated frequency divider, 13 is a second video signal input terminal,
14, 27° 35 is a switch circuit, 17 is a memory control circuit B222 is a field memory B123 is a field memo IJQ, 29 is a signal processing circuit during recording, 3
0 is a recording amplifier, 31 is a magnetic head, 32 is a magnetic tape, 33 is a reproduction amplifier, 34 is a demodulation circuit, and 36 is a video signal output terminal. Fig. 2 is a diagram for explaining the operation of each part during recording in Fig. 1, Fig. 3 is a trunk diagram showing an example of a recording trunk pattern in the present invention, and Fig. 4 is a diagram for explaining the operation of each part during reproduction in Fig. 1. 2 and 4, the numbers shown in FIGS. 2 and 4 indicate the operating states at the points with the same numbers in FIG. 1.

In FIG. 1, during recording, a first video signal is introduced into terminal 1, and this signal is introduced into vertical synchronization signal separation circuit 2 and field memo IJA 7.

The vertical synchronization signal 3 extracted by the vertical synchronization signal separation circuit 2 is input to the memory control circuit A4, and is used as a reference for writing to and reading from the field memory A7. Writing to the field memory A7 is controlled by a write signal 5, and one field of the first video signal (FIG. 2) is stored in the memory with reference to the vertical synchronization signal (FIG. 2). For reading, information stored in the memory is read out using a read signal 6 at a clock speed twice as fast as the writing clock, with the vertical synchronizing signal 3 as a reference. When writing and reading are repeated asynchronously as described above, a signal whose time axis is compressed as shown in FIG. 28 is obtained at the output 8 of the field memory A7. is introduced on the a side of On the other hand, a second video signal is introduced into the terminal 13, and this signal is transmitted to the vertical synchronizing signal separation circuit 15 and the field memory B22. It is introduced into the field memory 023. The memory control circuit B17 that controls writing to and reading from the field memo IJB 22 and the field memo IJC23 includes a vertical synchronization signal separation circuit 15.
A vertical synchronization signal 10 compressed in time axis is inputted to the bar obtained by supplying the vertical synchronization signal 16 extracted in 1 and the readout output 8 of the field memory 7 to a vertical synchronization signal separation circuit 9. Used as the standard for memory control signals. The writing to the field memory B22 is set, for example, for the period W shown in FIG. 2,
Only the odd fields of the second video signal (FIG. 2B) are written into the field memory B22. And the reading is the second
During the period W in FIG. 18, the vertical synchronizing signal 10 compressed to 1/2 in time axis is formed using, for example, an R-S flip-flop.
The information stored in the memory is read out at twice the clock speed per one notch. As a result, the time-base compressed signal shown in FIG. 24 is obtained at the output 24 of the field memory B22. Also, field memo I
To write to JC23, use the field memo IJB mentioned above.
The period is set as shown in FIG. 20, in which the polarity of the writing period (FIG. 2 18) to 22 is inverted, and only the even fields of the video signal of FIG. 2B are written to the field memo IJQ. Then, during the reading period W in FIG.
During the period shown in FIG. 2 formed using the -S flip-flop, information stored in the memory is read out using a clock that is twice as fast as the writing clock. As a result, the output 25 of the field memo IJ C23 contains the second
A time-base compressed signal shown in FIG. 25 is obtained. The signals 24 and 25 are mixed to become the signals shown in FIG. 26 and are introduced into the b side of the switch 2a. The switch 27 is switched between the a side and the b side by the level transition shown in FIG. As shown in FIG. 28, the first video signal B and the second video signal B are alternately derived in a time-axis compressed form. This signal is
After being subjected to the processing necessary for recording in the signal processing circuit 29, FM modulated, and amplified by the recording amplifier 3o, the magnetic head 3
1 is recorded on the magnetic tape 32. At this time, the rotating drum to which the magnetic head is attached rotates in synchronization with the vertical synchronization signal 10 that has been compressed in the time axis, and is set to rotate at the vertical synchronization period (the rotating drum in normal recording and reproduction is Figure 3 shows the trunk pattern on the magnetic tape recorded in this way, where ■ is the vertical synchronization signal position, and fv is the regular field frequency (NTSC 60Hz). As shown in the figure, the first video signal and the second video signal B are alternately recorded with the same vertical synchronizing signal position for each track, and are compressed into bars in terms of time.

During playback, a signal detected by a magnetic head 31 attached to a rotating drum rotating at twice the speed as during recording is amplified by a playback amplifier 33, and a fourth signal is detected by a demodulation circuit 34.
The signal is converted into a video signal shown in FIG. 28 and introduced into the p side of the switch 14. The switch 14 is switched to the p side during reproduction, and the reproduced video signal (FIG. 4, 28) is sent from the common terminal C to the vertical synchronizing signal separation circuit 15 and the field memo I.
Introduced in J 1322. Vertical synchronization signal separation circuit 15
The vertical synchronizing signal extracted in the step (FIG. 4, 16) is supplied to the memory control circuit B17, and the field memo IJ
This is used as the standard for writing to and reading from B22. The vertical synchronization signal (Fig. 4 16) is sent to the memory control circuit B1.
7 to V2 to generate a pulse signal as shown in FIG. 4, for example. This signal is used as a write signal to the memory, and whether to select and reproduce the first video signal or the second video signal B is determined by switching the switch 35 to the high level or low level shown in FIG. It is determined which period is used as the writing period to the memory. In other words, 13 If you want to select the first video signal person, switch 35
If you want to select the second video signal B with the high level period in FIG.
5 is set to the b side, and the low level period in FIG. 4 is set as the write period.

When the first video signal person is selected, the switch 35 is switched to the a side, and the write signal 18 to the field memo IJB becomes the period shown by W in FIG. 4 18-A. Reading is performed at the same timing as writing, as shown in FIG. 4, 19-A, and at a clock speed of the clock bar at the time of writing. As a result of repeating the above writing and reading asynchronously, only the first video signal is reproduced and outputted to the output terminal 36 as shown in FIG. or,
When the second video signal is selected, the switch 35 is
When the write signal 18 is switched to the side, the write signal 18 to the field memory B becomes the period shown at W in FIG. 4 18-B. The reading is performed at the same timing as the writing and with a clock having the same speed as the clock at the time of writing, as shown in FIG. 4, 19-B.

As a result of asynchronously repeating writing and reading for more than 14 pages, only the second video signal B is reproduced and output to the output terminal 36 as shown in FIG. 4, 36-B. Here, as an example, the configuration is such that either the first reproduced video signal or the second reproduced video signal is selected and reproduced, but the memory used during reproduction is increased, two receivers are prepared, It is also possible to obtain the first and second reproduced video signals simultaneously. Note that two field memories (field memories B and CX are used here) as the second video signal memory during recording, but this is for ease of explanation, and the memory for a minimum of 1.5 fields is used here. The same effect can be obtained by using field memory B22 in this example, but it may be field memory B or C (or field memory A), and field memory IJ C23 may be used for playback. When used, write and read signals 18 and 19 may be supplied to the memory 23 from lines 20 and 21.

In this way, the present invention compresses the time axis of a plurality of video signals having different phases and alternately forms vertical synchronization signals so that one field of each video signal is stored in one trunk. The drum rotates at a high speed according to the compression ratio so that all information is recorded, and during playback, only one of the video information is extracted and expanded in the opposite direction to that used during recording, so that the time axis is original. By returning it to , it becomes possible to obtain any one of the reproduced video signals. Note that the above example is 2
This is a configuration for recording and reproducing two video signals, but three
Even in the case of more than one video signal, this can be easily achieved by adding memory, setting the drum rotation speed, etc.

As described in detail, the magnetic recording/reproducing apparatus of the present invention is capable of recording all video signals of multiple channels on a tape by compressing the time axis and changing the number of rotations of the drum during recording.
At the time of playback, video signals of multiple channels can be recorded and played back by extending only the desired video signal component on the time axis, contrary to the time of recording. Therefore, there is an effect that video information is not lost in the recording and reproducing process, and reproduced images can be obtained with less deterioration in image quality such as screen flickering.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing device according to the present invention, FIG. 2 is a signal diagram for explaining the operation of each part during recording in FIG. 1, and FIG. 3 is a recording track according to the present invention. FIG. 4 is a track diagram showing an example of a pattern, and FIG. 4 is a signal diagram for explaining the operation of each part during reproduction of FIG. 1113...Input terminal, 2,9.15...
...Vertical synchronization signal separation circuit, 4,7...Memory control circuit, 7,22,23...Field memory, 14.27.35...Switch,
36...Output terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4

Claims (1)

[Claims] In a magnetic recording/reproduction device that records video signals on a magnetic tape by a rotating magnetic head while forming an inclined track at a rate of one track per field, a first video signal and a second video signal are input to the device. When the signals are given simultaneously, during recording, the first video signal included in the first video signal is
means for separating and extracting a vertical synchronization signal, and writing the first video signal into a memory one field at a time based on the first vertical synchronization signal, and reading the first video signal at the time of writing using the first vertical synchronization signal as a reference. a first memory means for obtaining a first video signal whose time axis is compressed to 1/2 by asynchronously reading it with a clock that is twice as fast as the clock of the second video signal; means for separating and extracting two vertical synchronizing signals, and writing the second video signal into a memory one field at a time based on the second vertical synchronizing signal, and reading the first vertical synchronizing signal from the first memory means. The time axis of the second signal is compressed to 1/2 by asynchronously reading it with a clock that is twice as fast as the writing clock at a predetermined timing based on the vertical synchronization signal included in the first time axis compression signal.
a second memory means for obtaining a video signal; a first time-base compressed signal read from the first memory means;
The second time-base compressed signal read from the memory means of
a switch means that alternately switches at the timing of the time-axis compressed vertical synchronization signal to produce one continuous time-axis compressed signal; The first time-base compression signal is supplied to one of the magnetic heads during half a revolution of the rotating drum, and the second time-base compression signal is supplied to the other head during the next half revolution to record the magnetic tape. During playback, the first of the playback signals from each magnetic head attached to a rotating drum that rotates at a vertical synchronization period is used.
or the second video signal component is written into the first or second memory, and reading is performed at one of the clocks at the time of writing.
The first or second time-base compressed signal is read out asynchronously with a clock having a speed of A magnetic recording and reproducing apparatus comprising: a reproducing means configured to simultaneously obtain the first and second reproduced video signals using a second memory and a second memory.