JPS61179686A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain simultaneous recording and reproduction of plural video signals having different phase without using a complicated composite head by controlling a drum while using the plural video signals as one signal and using a memory so as to record/reproduce other signals. CONSTITUTION:A V signal extracted by the 1st V signal extracting circuit 2 is fed to a drum servo and becomes a 2-level switch signal 5 to a changeover switch 3 via a 1/2 frequency divider 4. The V signal based on the 2nd video signal from the 2nd V signal extracting circuit 8 is subject to 1/4 frequency divider 11 and its output is fed to a write signal generating circuit 12, where two write (drive) pulse signals 13, 14 to field memories 9, 10, which can write the 2nd video signal during the signal pulse period. The phase of the 2nd video signal is synchronized nearly with the 1st video signal and led to the 2nd input terminal (b).

Description

[Detailed Description of the Invention] [Technical Field of the Invention 1] The present invention relates to a magnetic recording and reproducing device capable of recording and reproducing two video signals, and in particular, even if the video signals have the same phase, Such recording and reproduction can be easily performed.

[Technical Background of the Invention] In general, a magnetic recording/reproducing device (hereinafter referred to as a VTR) has a pair of heads mounted at different azimuth angles at 180° opposing positions on a cylindrical head drum, and a running magnetic tape. The video signal is recorded as a discontinuous signal and reproduced as a continuous signal by wrapping it in a helical shape of 180 degrees or more around the rotationally driven head drum and moving the head in contact with the diagonal width direction of the running magnetic tape. That's what I do.

[Problems with the background art] In a VTR having the recording/playback mechanism as described above,
When recording and reproducing video signals of multiple channels, it is necessary to use a number of VTRs corresponding to the number of channels, or to create a structure in which one pair of heads and another pair of heads each having the same azimuth are superimposed. . If the latter head is provided separately, the vertical synchronizing signal for one video signal can be recorded at the correct position on the tape pattern, but other signals will be inconsistent unless synchronized. Therefore, when selectively controlling switching with one display device, synchronization may be temporarily disrupted. Furthermore, it is difficult to select the width of the head, and there is also the potential problem of interference between the overlapping windings.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and is a method of recording a plurality of different video signals so that the synchronization signal positions match on a tape pattern, and switching them simultaneously or selectively. An object of the present invention is to provide a magnetic recording/reproducing device that can reproduce and display images.

[Summary of the Invention] In order to achieve the above object, a magnetic recording/reproducing device according to the present invention has two heads having different azimuth angles mounted on a rotating drum at positions facing each other by 180°, and tracks by each head on a running tape. In a magnetic recording and reproducing device that performs recording and reproduction by forming patterns diagonally alternately in the longitudinal direction of the tape, one video signal is used as a reference for head switching during recording, and this video signal is transmitted during the first half-rotation period of the drum. Recording is performed using only one head, and the other video signal is
Once stored in memory, it is read out during the second half-rotation period of the drum and supplied only to the other head, so that each video signal is alternately recorded on a predetermined track with the vertical synchronization signal position set to -. During playback, one track length of one of the two playback video signals derived from each head is stored in the memory again, and the readout signal and the signal from the head are switched and selected. It is constructed so that the images become one image.

[Embodiments of the Invention] The present invention will be specifically described below with reference to illustrated embodiments.

FIG. 1 is a circuit diagram showing an embodiment of a magnetic recording/reproducing device according to the present invention, FIG. 2 is a plan view showing the head arrangement of a rotating drum used in the present invention, and FIG. FIG. 4 is a time chart showing the generation timing of write pulse signals to the memory; FIG. 4 is a time chart showing the read timing of the same memory; FIG. 5 is a time chart showing the recording timing according to the present invention; FIG. 6 is related to the present invention. FIG. 7 is a track diagram showing an example of a track pattern, and FIG. 7 is a time chart showing timing during reproduction according to the present invention.

In FIG. 1, a first video signal is introduced into a terminal 1, and this signal is sent to a first The (2) signal is introduced into the input terminal a and extracted by the first V signal extraction circuit 2, and is supplied to the drum servo, and is also sent to the changeover switch 3 via the 1/2 frequency divider 4.
The level switching signal is set as level switching signal 5.

On the other hand, reference numeral 6 is a second video signal input terminal, and the signal from this terminal is sent to the second signal extraction circuit 8, field memory A9, and field memory via a recording (RFC) playback (PB) changeover switch 7. Introduced in B10. The V signal based on the second video signal from the second V signal extraction circuit 8 is divided into four by a quarter frequency divider 11 and its output is supplied to the write signal generation circuit 12 . This circuit 12 generates two write (drive) pulse signals 13° 14 to each field memory 9° 10 based on the 4-frequency divided output,
Each field memory 9.10 can be written with a second video signal during the pulse periods of these signals. however,
These write pulse signals are transmitted to the field memories 9 and 10.
are written and read operations alternately, so
The timing of the pulses is different. Furthermore, the field memories 9 and 10 can read memory signals using signals from the read signal generation circuit 15. This read signal generating circuit 15 generates read drive pulse signals 16 and 17 during one level period of the two-level switching signal 5 from the 1/2 frequency divider 4. However, in order to read the memory contents after confirming that they exist, check signals 18 and 19 derived from each field memory 9 and 10 are received at the end of writing, and these signals and the two-level switching signal 5 are
A read pulse signal is generated based on the logical product.

The signals thus derived from each field memory 9, 10 are respectively introduced into the second input terminal of the recording signal changeover switch 3. The switching state of the changeover switch 3 between the first and second input terminals a, b and the common terminal C is set by a two-level switching signal 5 based on the first video signal. Therefore, from the common terminal C, the first video signal included in the first level period of the two-level switching signal 5 and the second video signal included in the first level period of the two-level switching signal 5 are transmitted.
The second video signals read out from the field memory 9.10 during the level period are alternately derived. In other words, the second video signal is guided to the second input terminal with its phase substantially synchronized with the first video signal. Next, common end C
After being modulated by the modulator 31, the signal derived from the rotary transformer 21 is introduced into the primary side of the rotary transformer 21 via the recording amplifier 2.0, and from its output side is transmitted to each of the A and B heads 22.2.
3. Note that the reference numeral 24 is a magnetic tape.

The above is the configuration required for recording, but the configuration required for reproduction is as follows.

The signals detected by each head 22, 23 are
The output is introduced into the reproducing amplifier 25 via the transformer 21, and the output is sent via the demodulator 26 to the first output selector switch 27.
It is led out to input terminal a. Therefore, this first input terminal a
In this case, the first and V-second reproduced video signals appear alternately every half rotation of the drum. The second input terminal of this changeover switch 27 is adapted to read and derive the signals stored in the field memory A9 by a configuration described later, and the signals at these first and second input terminals a and b are By switching and selecting, each head A is connected to the output terminal 28 of the circuit connected to the common terminal C.

It is possible to derive only one of the first and second video signals alternately supplied from B.

That is, the signal selection switch 29 serves as a means for selecting the signal to be output to the output terminal 28. This switch 29
The first one is. The first playback video signal selection signal and the second playback video signal selection signal are received at the second input terminals a and b, respectively, and by setting the switching state by manual operation, for example, the above-mentioned signals are input to the common terminal C. Derive one of them. The signal from this common terminal C is sent to the exclusive OR circuit 30
A head switching signal is introduced into one input terminal of the circuit 30, and a head switching signal is introduced into the other input terminal of the same circuit 30. The output 31 of the exclusive OR circuit 30 is used as a switching control signal for the output selector switch 27 and is also supplied to the field memory A9. The signal 31 supplied to the field memory A9 and the output changeover switch 27 is a signal whose level changes every half rotation of the drum, and at the timing of this level transition, the field memory A9 is switched between the write state and the read state. are doing.

Further, the signal at the first input terminal a of the output changeover switch 27 is led to the Pa end of the recording/reproduction changeover switch 7, and during reproduction, the switch 7 conducts the Pa end and the common end C, thereby fielding the signal. The signal is supplied to the memory A9 and written at the timing of the output 31 of the exclusive OR circuit 3o. As a result, the output selector switch 27
The second input terminal of the input terminal a receives the reproduced video signal derived from the first input terminal a, which is a half-rotation period of the drum (one field period in this embodiment), that is, the signal reproduced from the field memory A9. A video signal can be derived. Note that the memory used during reproduction may be either the field memory 9 or 10, and if the field memory B10 is used, the signal 31 may be supplied to the same memory 10. Further, the second factor indicates the drum 32 in the present invention, and each head 22.23
The heads 22 trace the tape 24 during the first half-rotation period P1, and the head 23 traces the tape 24 during the second half-rotation period P2, each forming one track.

The present invention is constructed as described above, and its operation will be explained separately during recording and reproduction. However, the VTR to which this invention is applied is one that can record one field's worth of video signals on one track of the tape 24, but it may of course be applied to one that can record a plurality of fields.

(1) During recording The time charts related to the operation during recording are shown in FIGS. 3 to 5. First, the signals and timing charts shown in these figures will be summarized and shown.

Relationship in FIG. 3 (A)...Second video signal waveform, (B)...Write pulse signal 13 to field memory A9, (C)...Write pulse signal 14 to field memory B10, 4 Relationship (A>... ■signal extracted from the first video signal, (
B)...Two-level switching signal 5, (C)...V signal extracted from the second video signal, (
D), (E)...Same as Figure 3 (B) and (C), (F
), (G)...Check signal 18.19 to read signal generation circuit 15, (H), (I)...Read pulse signal 16.17, Relationship in Figure 5 (A)...Head is Timing for tracing the track (B)...First video signal waveform, (C)...Second video signal waveform, (D)...Field memory 80 writing timing, (E)...・Writing timing of field memory BIO, (F)... Recording timing of the signal read out from each field memory 9.10 to the head, (G>... Recording timing of the first video signal, (H )...2-level switching signal 5 Now, the first and second video signals are as shown in Fig. 5 (B) and (C
), the field frequency is within the broadcasting standard, but the phase is different. The first video signal is
It includes the ■ signal shown in Figure (A), and this signal is the first V
By using the servo signal from the signal extraction circuit 2 to the drum 32, the periods Pi and P2 during which each head 22, 23 traces the tape 24 are controlled based on the V cycle of the first video signal. The 1/2 frequency divider 4 divides the frequency of the above-mentioned (2) signal to produce a two-level switching signal that changes levels for each field as shown in FIGS. 4(B) and 5(H). This 2
The level switching signal 5 is set as a high level and low level signal, and the high level 1111! l] Record signal selector switch 3
If the setting is made such that conduction is established between a and C during the low level period and between b and c during the low level period, the P1 period becomes conductive during the high level period, and the P2 period becomes conductive during the high level period.
The period corresponds to the low level period. Therefore, the first video signal is supplied to the head side during the P1 period, and the signal from the field memory 9.10 is supplied to the head side during the P2 period.
always records the first video signal on its track A, and the head 23 always records the signal from the field memory 9-10 on its track B. This timing is shown in FIG. 5(G) with respect to the timing of the trace shown in FIG. 5(A).

T1 (period f when the first video signal is selected) shown in (F)
This can be understood from the fact that T2^ (the period during which the signal from field memory A9 is read) and T2O (the period during which the signal from field memory B10 is read) coincide.

By the way, the second video signal is written into each field memory 9, 10 at the timing shown in FIG. That is, in FIG. 3, <A) is the second video signal waveform, this signal is extracted by the 2V signal extraction circuit 8, and then the 4-minute signal (see FIG. 4(C)) is extracted. 1 divider 1
By dividing the frequency by 1/4, a signal (not shown) having a period of 2 frames is formed. The write signal generation circuit 12 determines from the above signal that the pulse periods tA and tB as shown in FIGS. 3(B) and 3(C) are equivalent to a half rotation period (one field period) of the drum 32, and that Periods tA and tB are 1/
Two write pulse signals with four periods are generated. However, each write pulse signal has a different half-cycle phase (one frame period).

In this way, the second video signal is alternately written into the field memories 9 and 10 every other field. Then, upon completion of the write pulse applied to each field memory 9.10, (D), (F) and (E) of FIG.
As shown in (G), check signals 18.19 are applied from each field memory 9.10 to the read signal generation circuit 15.

As is clear from FIG. 4(B), the check signals 18 and 19 have a signal period including the low level (Ill) of the two-level switching signal 5, and the two-level switching signal and the check signal are connected to the read signal generating circuit 15. The circuit 15 generates readout drive pulses 16 and 17 as shown in FIGS. 4(H) and 4(I). That is, pulses 16° and 17 are generated when the recording signal selector switch 3 is made conductive between b and c. As mentioned above, b-
Since the period during which conduction between t and c coincides with the period T2^, 72B during which the B head 23 traces the tape 24, the second video signal written during the period tA, tB is generated only by the head 23. and recorded on that B track. Thus, the first and second video signals are recorded, for example, in the diagonal width direction of the tape, with the positions of the ■ signals aligned as shown in FIG.

(2) During reproduction The operation during reproduction is shown in the timing diagram of FIG. This operation shows the operation when reproducing the first video signal, and in the figure, (A) is A.

The signal recorded on the B track is continuously shown and consists of a first reproduced video signal Ap and a second reproduced video signal BP. (B) shows a head switching signal, in which a signal from the head 22 is detected during a high level period, and a signal from the head 23 is detected during a low level period. (C) shows a signal for selecting the first reproduced video signal Ap, which is set to low level. (D) is exclusive OR circuit 3
0, the field memory A9 is set to the write state during the high level period, and the output selector switch 27 is set to conduction between C and A, and the field memory A9 is set to the read state during the low level period, and the switch is set to the write state. 27 is conduction between c and b. (E) shows the output reproduction signal. Incidentally, during reproduction, the recording/reproducing switch 7 is switched to select the signal from the PB side.

As is clear from the timings of (A) and (B), the reproduced signals derived through the rotary transformer 21 are the first and second reproduced video signals Aρ,
This is a signal that alternately contains Bp for each field. At this time, the signal selection switch 29 is set to a-Clil conduction, and the low level selection signal (C) is sent to the exclusive OR circuit 30.
When the head switching signal (B) is introduced, its output becomes a switching control signal that changes level at the same timing as the head switching signal (B), as shown in (D). Therefore, the output changeover switch 27 is
, coincides with the switching timing of B heads 22 and 23, and A
a when the first reproduced video signal Ap from the track is in a conductive state.
After being outputted to the output terminal 28 via the line B and C, at the next timing, the first reproduced video signal Ap' from the field memory A9 that is being read is output to the output terminal 28 via the line b and c in the conductive state. can lead to. In other words, the reproduced signal is repeated in the following order: first reproduced video signal Aρ from the head 22 → Aρ′ from the field memory A9 → Ap from the head 22, and becomes a continuous signal of the first reproduced video signal. . Incidentally, when selecting the second reproduced video signal, the signal selection switch 29 may be switched to guide a high-level selection signal to the exclusive OR circuit 30.

As described above, the present invention allows video signals having different phases to be recorded with their vertical synchronization signal positions coincident, and to be assembled into one of the video signals for display at the time of playback. becomes possible. Note that although the above embodiment is a configuration for recording and reproducing two video signals, the case of recording and reproducing three or more video signals can be easily achieved by increasing the memory and the like.

[Effects of the Invention] As explained above, according to the present invention, a plurality of video signals are drum-controlled using one signal as a reference, and other signals are recorded and reproduced using a memory, so that the phase This has the advantage that a plurality of video signals with different values can be simultaneously recorded and reproduced without using a complicated composite head.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a magnetic recording/reproducing device according to the present invention, FIG. 2 is a plan view showing the head arrangement of a rotating drum used in the present invention, and FIG. 3 is a diagram showing a memory provided according to the present invention. 4 is a time chart showing the read timing of the memory, FIG. 5 is a time chart showing the recording timing according to the present invention, and FIG. 6 is a track related to the present invention. FIG. 7 is a track diagram showing an example of a pattern, and a time chart showing timing during reproduction according to the present invention. 1.6...Input terminal, 2,8...Vertical synchronization signal extraction circuit, 3...Recording signal selection switch, 4...1/2 frequency divider, 5...2 level switching signal , 7... Record/playback selector switch, 9.10... Field memory, 1
1... Quarter frequency divider, 12... Write signal generation circuit, 13.14... Write (drive) pulse signal, 15
... Read signal generation circuit, 16.17 ... Read drive) pulse signal, 18.19 ... Check signal, 2
2.23...head, 24...magnetic tape, 27.
...Output selector switch, 28...Output terminal, 29...
- Signal selection switch, 30... exclusive OR circuit, 31
...Switching control signal, 32...Drum. Agent: Patent attorney Kensuke Chika (and one other person)
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Claims (1)

[Claims] Two heads with different azimuth angles are connected to one of the rotating drums.
In a magnetic recording and reproducing device that is mounted at 80° opposing positions and performs recording and reproducing by forming track patterns alternately in the width direction of the tape by each head on a running tape, the first and second video signals are transmitted during recording. 2. A means for deriving the vertical synchronization signal contained in the first video signal, dividing the frequency by a predetermined frequency, and shifting the level every half rotation period of the drum.
a signal forming means for forming a level signal; a first recording means for supplying a first video signal to one of the heads and recording it on the corresponding track pattern during a first level period of the two-level signal; Based on the output obtained by extracting the vertical synchronization signal included in the video signal of No. 2 and dividing it by a predetermined frequency, two write pulses whose pulse period is equivalent to a half rotation period of the drum and whose period occupies 1/4 period are generated. means for generating signals with different half-cycle phases; memory means for alternately storing second video signals in different areas during the pulse periods according to these write pulse signals; a second video signal read from the memory means by the reading means during a second level period of the two-level signal; a second recording means for supplying the signal to the other head and recording it on a corresponding track pattern; and during reproduction, one of the first or second video signal component of the reproduction signal from each head is converted into a reproduction signal. write signal selection means for writing into the memory means based on a selection signal and reading the written signal when another signal is being derived from a predetermined head; and a signal read from the memory means by this means. 1. A magnetic recording and reproducing apparatus comprising an output means for alternately switching and selecting the reproduction signal from each head and assembling the reproduced video signal as a first or second reproduced video signal to form one image.