JPS63224003A - Recording or reproducing method by helical scanning magnetic tape device - Google Patents

Abstract

PURPOSE:To continuously perform a recording or a reproducing by providing a forward direction travel recording area and a reverse direction travel recording area alternately along the longitudinal direction of a magnetic tape. CONSTITUTION:If the forming area of a forward travel recording track T1 is defined to be a forward direction travel recording area, and a space between each other of these is defined to be a reverse direction travel recording area, the scanning track T2 at the time of a reverse direction travel is formed between each other of the scanning tracks T1 at the time of a forward travel, shown by a dot line. Accordingly, even when the magnetic tape is made to travel in a reverse direction, a signal can be recorded or reproduced successively. Because at the time of the forward travel and the time of the reverse travel, the recording or the reproducing is performed by using the different area on the tape, the recording or the reproducing can be performed independently, and because the recording or the reproducing is possible for the reverse direction travel, an endless recording or reproducing or the recording or reproducing need not to be rewound can be easily performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording or reproducing method using a helical scanning magnetic tape recording device suitable for continuously recording video signals over a long period of time.

[Prior Art] In order to perform long-term recording using a helical scan VTR,
For example, the method of recording signals on half of the tape in the width direction, and then turning the tape cassette over once recording on this half area and recording the signals on the remaining half of the tape is, for example, the method proposed by Philips V -2000 system VTR etc. are well known.

[Problems to be Solved by the Invention] However, in the above method, the tape cassette must be turned over, so scanning performance is poor, and automatic long-term continuous recording or playback is impossible or difficult. be.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a helical scanning magnetic tape recording or reproducing method capable of recording or reproducing signals while the tape is running in both forward and reverse directions and recording or reproducing continuously. It's about doing.

[Means for Solving the Problems] To achieve the above object, the present invention provides a method for recording or reproducing signals by helically scanning a magnetic tape with a rotating magnetic head, in which the magnetic tape is scanned in a forward direction in the longitudinal direction of the magnetic tape. A regular recording area and a reverse regular recording area are provided alternately,
When the magnetic tape runs in the forward direction, the head scans the forward recording area to record or reproduce signals, and when the magnetic tape runs in the reverse direction, the head scans the backward recording area. The present invention relates to a recording or reproducing method using a helical scanning magnetic tape device for recording or reproducing signals.

[Function] In the above invention, the forward direction regular recording area and the reverse direction regular recording area are provided alternately along the longitudinal direction of the magnetic tape, so that even when the magnetic tape is run in the reverse direction, the signal cannot be transmitted. Sequential data can be recorded or played back. Since recording or reproduction is performed using different areas on the tape when traveling in the forward direction and when traveling in the reverse direction, recording or reproduction can be performed independently. Since recording or reproducing is possible even when traveling in the reverse direction, it becomes possible to easily perform endless recording or reproducing, or recording or reproducing without rewinding.

[Embodiment] Next, a helical scan VTR according to an embodiment of the present invention will be explained with reference to FIGS. 1 to 6. As shown in FIG. 1, the tape cassette 1 includes a pair of reels 2.3 and a magnetic tape 4, from one reel 2 to the other reel 3, and from the other reel 3 to one reel 2. It is configured to run the tape 4. In order to run the tape 4, a reel motor 5.6 is connected to the pair of reels 2.3.
A pair of capstans 7.8 and a pair of pinch rollers 9.10 are arranged along the running path of the tape 4, and a motor 11.12 is coupled to each capstan 8.9. There is. In FIG. 1, there are two tape guides 13.
14 is shown in principle, but in reality, more tape guides, impedance rollers, etc. are provided.

In order to helically scan the tape 4 by a pair of magnetic heads 15 and 16, the tape 4 is wound diagonally around a rotating drum 17 and a fixed drum 18 as shown in FIG. This helical scanning method is the same as that of well-known VTRs such as the VTR method and the β method, so a detailed explanation thereof will be omitted.

A pair of magnetic heads 15 and 16 for recording and reproducing video signals are attached to a rotating drum 17, and a drum motor 19 is coupled to the zero-rotation drum 17, which rotates together with the rotating drum 17. A pair of helads 15.16
is the recording/reproducing selector switch 21 via the rotary transformer 20.
It is connected to the. A recording circuit 22 is connected to a contact R of the changeover switch 21, and a reproducing circuit 23 is connected to a contact P.

The recording circuit 22 is a well-known VTR recording circuit that includes a low-pass filter, an AGC circuit, a clamp circuit, a pre-emphasis circuit, a clip circuit, an FM modulator, a high-pass filter, a recording amplifier, and a color signal recording system circuit. The regeneration circuit 23 includes a preamplifier, a channel switcher, a high-pass filter, a dropout compensation circuit, a limiter, an FM demodulator, a de-emphasis, a low-pass filter, a noise reduction circuit, an output circuit, and a color signal regeneration system. Well-known VTRs including
This is the same as the regeneration circuit. The recording circuit 22 has an input terminal 24
For example, the video signal of NTSC system is supplied from the source, and it is played back! ! 823 outputs a video signal to the output terminal 25.

The VTR of this embodiment has a first
, second, third and fourth erase heads 26a, 26b
, 27a and 27b. First erase head 26a
is set at an angle θ1 relative to the first video head 15 in order to perform erasing before the first video head 15 during forward running.
is placed first. The second erasing head 26b is arranged ahead of the second video head 16 by an angle θ2 in order to perform erasing before the second video head 16 during forward running. The third erasing head 27a is arranged ahead of the first video head 15 by an angle θ3 in order to perform erasing before the first video head 15 during reverse running. The fourth erasing head 27b is arranged at an angle θ4 greater than the second video head 16 in order to perform erasing in advance of the second video head 16 during reverse running.
is placed first.

The first and second video heads 15 and 16 are arranged at the same height relative to the rotating drum 17 as in the past, but newly provided first to fourth erasing heads 26a
, 26b, 27a, and 27b are fixed to the rotating drum 17 at positions different from the video head rotating surface 28, as shown in the developed views of FIGS. 3 and 4. In FIG. 1, θ1=θ2=θ3=θ4=θ, and the fifth
If the distance between the center and the center of the slide shown in the figure is d, the height difference H from the video head rotating surface 28 is (θ/18G) x d
is set to be. First and second erasing heads 2
6a and 26b have a track width that allows the scanning areas of the first and second video heads 15.16 to be erased in advance, as shown in FIG. is also placed above. When the tape 4 is to run forward, the drum 17 is rotated counterclockwise in FIG. 1.

Therefore, in FIG. 3, the scanning track is formed from the lower left to the upper right, and the first and second erasing heads 26a,
26b precedes Rad 15.16 to the first and second videos.

The third and fourth erasing heads 27a and 27b are connected to the drum 1.
The first and second video controllers 15 have a track width that allows the scanning area of the first and second video controllers 15 and 16 to be erased in advance during reversal (reverse rotation) of
．． It is arranged below the rotating surface 28 of 16. When reversing, a scanning track is formed from the upper right to the lower left in FIG. 4, so the third and fourth erasing heads 27a, 2
7b precedes the first and second video heads 15.16.

Fifth [! I shows a track pattern when the tape 4 according to the present invention is run in the forward direction for recording, as viewed from the magnetic surface side of the tape 4. The distance d between the centers of the tracks T1 is set to be sufficiently larger than that of a general VTR. That is, the interval d is determined so that a blank area of at least one track width is generated. This interval d
can be easily obtained by changing the running speed setting of the tape 4. Now, if the forming area of the forward running recording track T1 is defined as the forward direction regular recording area, and the space between these is defined as the reverse direction regular recording area, then the forward direction regular recording area and the reverse direction regular recording The regions are arranged alternately.

FIG. 6 shows the pattern of the scanning track T2 when the tape 4 is running in the reverse direction and the drum 17 is rotated in the reverse direction to record or reproduce the first and second videos at rad 15.16. The scanning track T2 during forward movement occurs between the scanning tracks T1 during forward movement shown by dotted lines.

To explain FIG. 1 again, the control circuit 29 performs the following four controls during recording.

(1) The video heads 15 and 16 are rotated synchronously to correspond to the frequency 172 of the vertical synchronization signal of the video signal at the input terminal 24.

(2) Controlling the relative position of the heads 15, 16 and the tape 4 so as to record the vertical blanking period on the tape 4 at the beginning of writing a track.

(3) The control head 34 records a control track signal indicating the position of a recording track necessary as a reference during reproduction on a part of the tape.

(4) Running the tape 4 at a constant speed.

Further, the control circuit 29 performs control for faithfully tracking the heads 15, 16 over the recorded video track during playback.

In order to execute the control as described above, the capstan motor 11 is connected to the control circuit 29 via the drive circuit 30,
A frequency generator 31 that detects the speed of the capstan motor 11 is also connected to the control circuit 29 . Further, the drum motor 19 is connected to a control circuit 29 via a drive circuit 32, and a frequency generator 33 for detecting the speed of the drum motor is also connected to the control circuit 29. Furthermore, a control (CTL) head 34 records and reproduces control signals.
．． 35 and a PG head 36 that generates a pulse every time the drum 17 rotates once, and these are also connected to the IIN control circuit 2.
9 is connected. In order to input an NTSC video signal, the control circuit 29 connects the input terminal 2 with a line 37.
Connected to 4.

The control circuit 29 is constructed using the same principle as that of VTRs such as the VHS system and the β system, so a detailed explanation thereof will be omitted.

This device includes a running direction switching circuit 38 for automatically switching between running the tape 4 in the forward direction and running in the reverse direction. This running direction switching circuit 38 selectively generates a first level (high level) output that instructs forward running, and a second level (low level) output that instructs reverse direction running.

A start sensor 39 is provided to detect the recording or playback start point (starting end) of the tape 4, and an end sensor 40 is provided to detect the recording or playback end point (end) of the tape 4. It is connected to the running direction switching circuit 38. The output of the running direction switching circuit 38 is the drive circuit 30 for the capstan motor 11 and the reel motor 5.6.
．． 41 and 42, respectively, and the pinch roller 9
．． 10 drives 43,44 are also connected.

[Recording Operation] When performing forward recording, the capstan 7 is caused to check the pinch roller 9, and the tape 4 is run at a constant speed in the forward direction shown by the arrow 46 in FIG. Further, the drum 17 is rotated counterclockwise (forward direction) in FIG. This allows the first
and second erasing heads 26a and 26b scan the tape 4 obliquely, followed by the first and second video heads 1
5.16 scan. As a result, as shown in FIG.
recorded in Further, a control signal 48 is recorded in the control track area 4b by the main control head 34 once per rotation of the drum 17.

This control signal consists of repeated recordings of north and south poles. In addition, in this method, when recording forward running, the sub control head 35 monitors whether a control signal has already been recorded before the main control head 34, and if it is detected that the control signal has already been recorded, does not record a new control signal, but plays back the control signal that has already been recorded, determines the track position to be recorded using the video RAD 15.16 from the playback control signal, and continues recording while controlling it. .

When the end sensor 40 detects the end of forward running of the tape 4, the running direction switching circuit 38 outputs a reverse running signal in response. Capstan motor drive circuit 30
, reel motor drive circuits 41 and 42 operate the capstan motor 11 and the reel motor to reverse the tape 4 from the forward direction shown by arrow 46 in FIG. Drives 5.6. This reversal control is performed in exactly the same way as auto-reverse in an audio tape recorder. Further, one drive device 43 consisting of a plunger solenoid etc. is turned off and one pinch roller 9 is separated from the capstan 7, and the other drive device 44 is turned on and the other pinch roller 10 is moved away from the capstan. Transition to 8. At the same time, the motor 19 of the drum 17 is driven to rotate in reverse (clockwise direction). The main control head 34 detects the control signal 48 recorded during forward regular running, and based on this, the relative positional relationship between the video head 15, 16 and the tape 4 during reverse regular running is determined. When traveling in the forward direction in FIG. 5, the distance between the control head 34 and the end of the track T1 is controlled to be Xl, but when traveling in the reverse direction in FIG. 6, it is controlled so that it becomes XI + X3 = X2. Ru.

Note that X3 is 174, which is the mutual interval P of the control signals. As a result, a scanning track T2 during regular movement in the reverse direction is generated in a blank area between the forward scanning tracks T1 indicated by dotted lines in FIG. This backward running track T2 is formed by the video tape 16 running diagonally from the top to the bottom of the tape 4 in FIG. Even during this reverse movement, the third and fourth erasing heads 27a, 27
b is erased first, and then the signal is recorded.

When the starting end of the tape 4 is detected by the start sensor 39 while running in the reverse direction, a forward direction signal is output from the running direction switching circuit 38, and the tape 4 returns to the forward running state.
The signals recorded during the first forward run are the first and second
erased by the first erase heads 26a and 26b, and then erased by the first erase heads 26a and 26b.
and the second video head 15, 16 records the signal. As a result, only the newest input signal is accumulated (recorded) in the section corresponding to the round trip time of the tape 4.

[Playback operation] During playback, the main control head 34 detects a control signal 48, and this playback control signal causes the first and second video heads 15, 16 to be aligned in the positional relationship shown in FIG. 5 when traveling in the forward direction. The relative positional relationship with the tape 4 is controlled, and the above-mentioned relative positional relationship is controlled so that the positional relationship shown in FIG. 6 is achieved when traveling in the reverse direction.

According to the above method, reciprocating recording and reproducing is possible with only slight changes to the basic mechanism of a general helical scan VTR. Furthermore, automatic reversal of the running direction at the end of the tape enables continuous long-term recording and playback or endless recording and playback.

[Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(1) It is also applicable to reel-to-reel type VTRs.

(2) It is also applicable to recording and reproducing audio signals, etc.

(3) It is also applicable to analog recording or digital recording without FM recording.

(4) The sub control head 35 may be omitted, a control signal may be recorded by the main control head 34 during the first forward run, and thereafter this control signal may be used for recording and reproduction. A tape with recorded signals may also be used.

(5) The sub control head 35 may be moved to the left side of the drum 17 near the capstan 8.

(6) As shown in Figure 7, θ1=θ2-θ3=θ4=9
The first to fourth erasing heads 26a, 2
6b, 27a, and 27b may be arranged.

(7) A plurality of forward recording tracks T1 may be arranged close to each other and grouped, and a group of reverse recording tracks may be recorded between these groups, i.e., a single forward and reverse recording area may be formed. A plurality of tracks may be included, or the rotational direction of the drum 17 may be kept the same as during forward recording when performing reverse recording.

[Effects of the Invention] As is clear from the above, according to the present invention, long-term continuous recording or reproduction, or endless recording or reproduction can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the principle of a VTR according to an embodiment of the present invention, FIG. 2 is a front view showing the drum section of FIG. 1, and FIG. Figure 4 is an exploded view showing the video head and the first and second erasing spatulas as seen from the outside of the rotating drum. Figure 5 is a plan view showing the recording track when traveling in the forward direction, Figure 6 is a plan view showing the recording track when traveling in the reverse direction, and Figure 7 is a developed view showing the head arrangement of a modified example. . 4...Tape, 15.16...Head, 17...
Drum, 22... Recording circuit, 23... Playback circuit, 2
9... Control circuit, 38... Running direction switching circuit.

Claims (1)

[Scope of Claims] [1] A method for recording or reproducing signals by helically scanning a magnetic tape with a rotating magnetic head, comprising a forward running recording area and a backward running recording area in the longitudinal direction of the magnetic tape. are provided alternately, and when the magnetic tape is running in the forward direction, the head scans the forward recording area to record or reproduce signals, and when the magnetic tape is running in the reverse direction, the backward recording area is scanned by the head. A recording or reproducing method using a helical scanning magnetic tape device, characterized in that signals are recorded or reproduced by scanning with the head.