JPS5981983A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent large rolling at the upper part of a screen excellently by providing a correcting device which equalizing the amount of jumping of a horizontal synchronizing signal caused by the switching of auxiliary heads all the time. CONSTITUTION:A 0.5 delay circuit 4 delays the playback output of an auxiliary head 12b or 22b by 0.5H (H; horizontal scanning period) in the 1st intermittent run of a magnetic tape. Consequently, an interval between horizontal synchronizing signals is increased forcibly from 0.75H to 1.25H in switching the heads 12b and 22b to secure an H jump of 0.25H. The circuit 4 is started by a switch 5 during the next intermittent run, but delay of 0.5H is not done in the next intermittent run, so subtraction between 0.75H and 0.5H is performed eventually to make an H jump of 0.25H. Therefore, a special reproducing device 1 fixes the H jump caused by the switching between the heads 12b and 22b to 0.25 in the same direction all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magnetic recording/reproducing apparatus having a special reproduction function by intermittent driving of a magnetic tape.

BACKGROUND ART Some magnetic tape recording/reproducing formats have a tape pattern in which the horizontal synchronizing signals between adjacent tracks are recorded with a shift of one water cycle H, for example, by T. On the other hand, for special reproduction of magnetic tapes, in addition to a pair of main heads with different azimuth angles provided for standard recording and reproduction, an auxiliary head for reproduction only having the same azimuth as one of the main heads is provided. A special playback device is known in which a head repeatedly traces the same track to obtain a playback output, thereby reproducing one frame of the screen with a playback signal from the same track.

However, even with the above-mentioned special playback device, in the standard playback mode, the playback track traced by the main head sequentially moves to the next track, and the discontinuity of the horizontal synchronization signal (hereinafter referred to as H jump) occurs at the joint of the playback output. However, in the slow playback mode using intermittent drive, there is still image playback and playback by moving the tape (repeated).
When playing back still images or when moving a tape, a jump occurs immediately after the auxiliary head is switched, so a discontinuity in the horizontal synchronization signal occurs at the joint of the playback output, causing the edges of the screen to curve. A so-called skew distortion phenomenon occurred.

However, in the case of still image playback in which the same track is repeatedly traced using a so-called H-aligned magnetic tape in which the recording position of the horizontal synchronization signal is not shifted between adjacent drags, for example, as shown in Figure 1, , l Track pitch is traced diagonally, so h1+h compared to standard playback.
No skew distortion occurs due to extra reproduction of 2-O5H. In addition, as shown in Fig. 2, even when reproducing across tracks at the same speed as during recording, an additional amount of h3+h4=lH is regenerated, so that reproducing can be performed without any inconvenience.
, 2, A1, B1, A2, B2...
represent adjacent tracks, and the dotted line represents the position where the head switching signal is output. Further, the arrow indicates the scanning direction of the head.

On the other hand, when using a magnetic tape in which the recording position of the horizontal synchronization signal described above is shifted by 0.23 H between adjacent tracks, the magnetic tape is driven intermittently during slow playback due to intermittent drive and the playback track is switched. Moreover, since the amount of H jump changes from before, there is a drawback that a large amount of horizontal shaking occurs at the top of the screen. This occurs during still image playback, as will be explained in conjunction with Figure 3 '1 in the following section of the disclosure of the invention. ; For the H jump of H, 0.2 in the opposite direction when magnetic tape is driven intermittently.
! ; As a result of the H jump of H, the overall result is 0.
! This was because the H-) Young of H appeared as a fluctuation in skew distortion.

In order to eliminate this skew distortion of F[i, for example, a special playback device uses different delay circuits to delay the playback output every time the magnetic tape is stopped and the head is switched during slow playback, and when the magnetic tape is driven. is also known, but this method has drawbacks such as flicker that tends to appear on the screen because the delay circuit is switched on and off in accordance with the switching of the auxiliary head.

DISCLOSURE OF THE INVENTION The present invention provides a method for adjusting the playback output of an auxiliary head dedicated to slow playback by 0.2 JH during slow playback of a magnetic tape in which the recording positions of horizontal synchronizing signals are shifted by 0.2 JH between adjacent tracks. By delaying the playback track by J H every other time when switching the playback track, the defect mentioned above is eliminated, and all the H jumps that occur when switching between the two auxiliary heads are set to O,,2j H, and the large part at the top of the screen is It is an object of the present invention to provide a magnetic recording/reproducing device which prevents horizontal shaking.

In order to achieve this objective, the present invention provides a magnetic recording and reproducing system that is equipped with a pair of auxiliary heads for special reproduction, which have almost the same azimuth angle as one of the main heads, in addition to a pair of main heads for standard recording and reproduction. When performing slow playback by intermittent drive of a magnetic tape on which recording positions of horizontal synchronization signals between adjacent tracks are shifted by 0.23 H, the playback output of the auxiliary head is changed when switching between playback tracks. 0 every t times. j H delay, the H jump caused by switching the auxiliary head is always 0.2! ;
The gist of the present invention is to provide a correction means for setting H.

According to the magnetic recording and reproducing device of the present invention, during slow playback, Ω corresponds to the misalignment that occurs during still image playback.
2! ; In contrast to H jump, when switching the playback track due to intermittent driving of the magnetic tape, O! By delaying the playback output of the auxiliary head by H and canceling the delay when switching to the next playback track, the H jump that occurs in the opposite direction is corrected, and the phase that occurs when the two auxiliary heads are switched is corrected. The jump is always the same amount, which eliminates the large lateral shake that occurs in the screen and parts, which was a conventional drawback, and the playback output delay is only 7 times when switching the playback track. Since this is performed every other time, compared to other systems in which switching of the auxiliary head is performed with a different delay, it has excellent effects such as less flicker appearing on the screen.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. 3 and 1 are diagrams for explaining the tape patterns of magnetic tapes that are not arranged in H order, respectively, and the left diagram is a schematic circuit configuration diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention. and FIG. 6 (Shu to F) are signal waveform diagrams of various parts of the magnetic recording/reproducing apparatus shown in FIG. 5, respectively.

In the left figure, the video signal line 1 of the magnetic recording and reproducing apparatus is a pair of main heads 2a for standard recording and reproducing.

In addition to 2b, in this embodiment, there is a pair of auxiliary heads dedicated for special playback, which have approximately the same azimuth angle as the main head 2b, and are angularly divided by 1ro0. It is a so-called helical scan type Hirohead type device, which is equipped with t) and 22b. In the magnetic chip 3 used, as shown in Figures J and 11, the recording positions of the horizontal synchronizing signals are not aligned in H, and adjacent tracks A1 and B1 are
The recording position of the horizontal synchronization signal is shifted by O, XH. In the figure, the dotted line indicates the position where the head switching signal sh is output. Note that if this type of magnetic chip 3 is played back in slow motion in the normal manner, when playing still images along the trajectory shown in FIG. , the interval between recording positions of adjacent horizontal synchronization signals is h1+h2=/, -25H, and a phase jump of 0ΔH occurs, whereas in normal speed playback by intermittent drive along the trajectory shown in Fig. φ,
When switching from track B1 to the next track B2, as the auxiliary head /2'F) and 22b are switched,
The interval between recording positions of adjacent horizontal synchronization signals is b3+h4=0
．． 7! ;H, and an H jump of v5H occurs in the opposite direction. As already explained, as a result, a large lateral shake equivalent to 0, j H minutes occurs on the screen and the screen.

Here, a pair of auxiliary heads exclusively for special playback l,
3. ．． 1. The reproduction output of b is 0, 5 I(
The signal is supplied to the delay circuit ψ and its bypass line lla, and is selectively taken out by a switch 5 that is switched in synchronization with the switching of the reproduction track during slow reproduction. AND gate circuit 7 which uses an inverter t to invert the auxiliary head switching signal S)1 and a gate signal which is the inverted output of the inverter B, and transmits and controls pulses based on the back electromotive force generated during coasting among the capstan drive signals. , furthermore, the trigger circuit r connected to the AND gate circuit 7, the free-lag frog circuit 9 connected to the trigger circuit r and switching the switch S, etc., are connected to the a5H delay circuit and the switch S.
Together, they constitute a correction means.

Below, regarding the operation of the magnetic recording and reproducing device having the above configuration,
FIGS. 6(A) to F') will also be explained.

The capstan drive signal Sc during slow playback is shown in Fig. 6 (
As shown in A), a positive polarity drive pulse SCa for rotating the cab stan in the magnetic tape feeding direction, a negative polarity braking pulse scb and coasting that are issued after a coasting time after the disappearance of the drive pulse Sea, and coasting. It consists of a pulse SCC based on the back electromotive force at the time. The leading edge of the braking pulse Scb is controlled to fall at the same timing as the control signal SCO delayed by ΔT from the trailing edge of the drive pulse Sca, as shown in FIG. 4(0).

On the other hand, the head switching signal Sh of the auxiliary head is as shown in FIG. 6(D).
b is obtained every 11 predetermined rotations and therefore has a constant period. Therefore, the inverting output surface of inverter B becomes as shown in FIG.

Furthermore, the other input of the AND gate circuit 7 is the sixth
As shown in the figure (j3), the capstan drive signal So
Of these, the pulse Scc' is output for the same time as the pulse Scc based on the back electromotive force during coasting that is sandwiched between the drive pulse Sca and the braking pulse Scb. This pulse scc' is obtained from an intermittent drive circuit for slow reproduction.

Therefore, the trigger circuit t connected to the AND gate circuit 7
As shown in Figure (F), whenever the auxiliary head is turned while the magnetic chip 3 is coasting, the trigger output St is supplied to the subsequent flip-flop circuit. For this reason,
The switch is switched each time the magnetic tape 3 is intermittently running.

In this example, the magnetic tape is intermittently run for two tracks to perform normal playback of 1 frame, then the magnetic tape is stopped for the next two tracks to play still images, and this is repeated. Slow playback is being performed.

Here, during the first intermittent running of the magnetic tape 3, the OjH delay circuit da is activated by the auxiliary head 12. The playback output of either 2.b or 2.2b is delayed by ajH.

As a result, the interval between the horizontal synchronizing signals is 0.7! , from H/, 2! ; Forced expansion to H, 0.2 J
H jump of H can be secured.

Also, the next time you run intermittently, 0. Unfortunately, the H delay circuit Hiro was opened by a switch, but this is because there will be no delay of 05H in the next intermittent run, so the subtraction of 0.7 i H and ajH will be performed as a result. This is because the H jump becomes a2 left H.

In this way, the special playback device l having the above configuration can always make 0.2 j H jump in the same direction with respect to the H jump that occurs when switching between the auxiliary heads /2b and 2.2b, which eliminates the conventional drawbacks. It is possible to effectively prevent the large horizontal shaking that occurred in the screen and parts of the screen.

Also, with the auxiliary head 2b! , 2b, the flicker that appears on the screen is extremely small compared to other systems that have different delays in switching.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining tape patterns of H-arranged magnetic tape, respectively. 11 is a diagram for explaining the tape pattern of a magnetic tape that is not arranged in an H arrangement, FIG. 3 is a schematic circuit diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention, and FIG. ) to F) are signal waveform diagrams of various parts of the magnetic recording/reproducing apparatus shown in FIG. 3, respectively. l...Video signal system line 1.2 of magnetic recording/reproducing device
a,, 2b...Main head, /Jb, 3.2b...Auxiliary head, 3...Magnetic tape, A1. A2. A3. B
1. B2...Track, G...O, J H postponement circuit,! ···switch.

Claims (1)

[Claims] This is a two-head helical force scan type magnetic recording and reproducing device that performs recording and reproducing using two heads with different azimuth angles, and horizontal synchronization signals are recorded between adjacent tracks at In a magnetic recording/reproducing device that reproduces a recording pattern with a deviation of 1/2/horizontal synchronization period, in order to perform slow reproduction, a magnetic recording/reproducing device that has the same azimuth angle as one of the main heads for normal recording/reproduction is used. A pair of auxiliary reproducing heads spaced apart from each other by /1000 angle interval are provided, and when performing slow reproduction by intermittently driving the recording medium while overlappingly tracing the same track, when reproducing the recorded pattern, the auxiliary head The playback output is multiplied by the phase shift of the horizontal synchronization signal between the tracks, or n+0. ! ;H (n is O or a positive integer) playback signal delay circuit is repeatedly inserted and released every time the playback track is switched, and the horizontal synchronization signal jumps that occur when the auxiliary head is switched. A magnetic recording/reproducing device characterized by comprising a correction means for always keeping the amount the same.