JPS6232783A - Magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate noise occurring in a switching time and to suppress the turbulence of a picture plane by using a head having a larger output during until a tracking servo is stabilized in the switching time between a still reproducing or a high speed reproducing and a regular reproducing. CONSTITUTION:A still reproducing command signal 16 and a high speed reproducing command signal 17 are supplied to a delay circuit 21, and a delay signal 22 delayed by a prescribed time from the leading edge or the trailing edge of each command signal is outputted. The delay signal 22 is given to all of heads 1-4 through a head switching circuit 15. When the heads 1 and 2 are contacting with a tape 6, the head having a larger output signal out of the heads 1 and 2, or when the heads 3 and 4 are contacting with the tape 6, the head having the larger output signal out of the heads 3 and 4 is selected and reproduced. Thereby, it is possible to suppress the turbulence of the picture plane in the switching time from a reference mode to the still reproducing or the high speed reproducing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/playback device having a special playback function, and particularly to prevention of screen disturbances when changing the playback state.

[Conventional technology]

Figure 3 is a circuit diagram showing a conventional magnetic recording/playback device with special playback functions such as still playback and high-speed playback. In Figure 2, (1) to (4) are provided on the drum (5). ,
These are playback heads that pick up signals recorded on the magnetic tape (6), (1) is the R azimuth head for 3x mode, (2) is the L azimuth head for standard mode, (
32 is the L azimuth head for 3x mode.

(4) is an R azimuth head for standard mode. (7)
~α values are the amplifiers that amplify the reproduced signals picked up by each of the heads (1) to (4), α8ii the amplifier +71. (A comparator that selects the larger one of the outputs of 81, σa is the above amplifier +91. A comparator that selects the larger of the outputs of aS is the output of the comparator aυ or a derived through this changeover switch, the first head switching signal αY, the still playback command signal αG, and the high-speed playback. A head switching circuit which introduces a command signal αD and a standard-3x mode switching signal αa and generates a second head switching signal Ilj using these signals; 1) to (4) output signals.

This is a video reproducing circuit that selectively takes in the first and second head switching signals α to α1 and reproduces video 1 & corresponding to a desired mode. That is, for normal playback in standard mode, the standard mode head (2+, f4+; for normal playback in 3x mode, the 3x mode head) "fl+".

The output signals of (3) are selected respectively and normally reproduced by the video reproduction circuit (2). Also, in still playback in 3x mode, head +11. The +41 output signal is selected to achieve a field steal without pre-presence, and the head +1) and t3+ output signals are selected for high-speed playback in the 3x mode. Furthermore, in still playback in standard mode, head +21. +31 output signal is selected to realize field still, and high-speed playback in standard mode uses all heads ill~(4) and head (1).

(2) side is in contact with the magnetic tape (6), head t11. (The larger of the 2+ output signals is sent to the head (3).

(4) When the sides are in contact, head +31. +41
The larger output signal of each is selected to achieve noise-free high-speed playback.

[Problem that the invention seeks to solve]

The conventional device is constructed and operates as described above.

Here, head for 3x mode +11. By making the width of +31 larger than the video track width of 19 μn in 3x mode, there will be no unrecorded part (girt band) than K, and therefore still playback in 3x mode.

It is possible to reduce noise at the time of starting and canceling high-speed playback. On the other hand, since the standard mode head (2) is not used in the 3x mode, the head width can be made sufficiently wide, but the head (4) is also used in the 3x mode (during still playback) as described above, so the head width can be made sufficiently wide. If the width is made wider, the image quality etc. will deteriorate, so it cannot be made wider. Therefore, it is necessary to make the video track width smaller than 58 .mu.n, and a guard band is created.

In the conventional device, the head switching circuit a5 operates in response to the rise and fall of the still playback command signal (Ie) for still playback in the standard mode, and the rise and fall of the high speed playback command signal aη for high speed playback. However, as mentioned above, the standard mode head (
4) is used for still playback in the 3x mode, so it needs to be narrower than the track width of 58μ. Therefore, when transitioning from normal playback in standard mode to still playback.

The used head immediately becomes +21. +41 to (21, +3
1, both sides are disturbed until the noise is removed from the screen, and conversely, when returning from still playback to normal playback, until the tracking servo stabilizes and the head completely traces the track. It also makes noise easily. When transitioning from normal playback in standard mode to high-speed playback, high-speed playback uses all heads t1) to (4) as described above, and heads (1) and +21 are in contact with tape (6). When the output signal is larger among (1) and (2), the head +31. +31 when +41 is in contact with tape (6). By selecting the larger output signal of +41, noise is prevented from appearing, but on the other hand, when returning from high-speed playback to normal playback.

The used head immediately becomes +21. Since it switches to +41,
Noise occurs until the tracking servo stabilizes.

This invention was made to solve this problem, and it causes noise and 11 screen disturbances when transitioning from normal playback to still playback to high-speed playback in standard mode, and conversely when returning to normal playback. The purpose of this invention is to obtain a compact magnetic recording/playback device.

[Means for solving problems]

The magnetic recording/playback device according to the present invention operates at high speed until noise is removed from the screen when transitioning from normal playback to still playback operation, and until tracking servo stabilizes after returning to still playback or high-speed playback. As with speed playback, the head with the larger output was used. To be more specific.

A delay circuit is provided in the still playback command signal and high-speed playback command signal circuits, and a delay signal of a certain width is provided at the rising and falling points of the still playback command signal, and a delay signal of a certain width is set at the falling point of the high-speed playback command signal. , and these delayed signals are supplied to the head switching circuit.

[Effect]

The delay time of the delayed signal at the rising edge of the still playback command signal is defined as the time until the noise is driven out of the screen, and the delay time of the delayed signal at the falling edge of the still playback command signal is defined as the time required to return from still playback to normal playback. By setting the time required for the tracking servo to stabilize, and further setting the delay time of the delay signal at the falling edge of the high-speed playback command signal as the time required for the tracking servo to stabilize after returning from high-speed playback to normal playback, these changes can be achieved. By using the delayed signal, all the heads can be used, and the head with the larger reproduction signal output of the adjacent heads can be selected for reproduction, so that noise can be reduced.

[Embodiments of the invention]

FIG. 1 is a circuit diagram showing an embodiment of the magnetic recording and reproducing apparatus according to the present invention, in which D, +11 to (1) are completely the same as the conventional apparatus described above. Qυ is a capacitor.

This is a delay circuit composed of resistors, etc., and the delay signal @ is input to the head switching circuit q1, and at the start of still playback in standard mode and the end of still playback and high-speed playback, the head with the larger output is switched. is selected to suppress noise.

FIG. 2 is a waveform diagram for explaining the operation of FIG. 1,
At the rising and falling points of the still playback command signal, t
A delayed signal with a delay of l and +2 and a delayed signal with a delay of +5 at the falling edge of the high-speed reproduction command signal αη are respectively derived and supplied to the head switching circuit α1. tIU noise is removed from the screen; +2 is the time it takes for the tracking servo to stabilize after returning from still playback to normal playback; +5 is the time it takes for the tracking servo to stabilize from high-speed playback to normal playback D) time until the tracking servo stabilizes shall be. When the above delay is applied, all heads (1) to (4) are used by this delay signal (a) via head switching circuit α9, and heads (il) and (2) come into contact with tape (6). When heads 13+ and +41 are in contact with the tape (6), use the head with the larger playback signal output among the heads 1d11> and +2), and when the heads 13+ and +41 are in contact with the tape (6), select the head with the larger playback signal output among the heads 1d11> and +2). The head can be selected and played. The screen is distorted when changing the playback status.
This is because the head does not pick up the signal on the tape or the track and the head are misaligned.Heads +1) and +2+ and heads (3) and (4) are adjacent to each other, so the difference between these two heads is Even if one side is not picking up the signal, the other may be picking up the signal. Therefore, by selecting the higher reproduction level, it is possible to suppress screen disturbances at the time of transition.

〔Effect of the invention〕

As mentioned above, this invention uses a still playback command signal.

A delay circuit is provided in the high-speed playback command signal circuit, and a delay signal is derived at the rise and fall of the still playback command signal and at the fall of the high-speed playback command signal, and all heads are selected by this delay signal. As a matter of fact.

It is assumed that the head with the larger reproduction signal output of the adjacent heads is used for reproduction. 2. When transitioning from the normal reproduction state to the special reproduction state.

Or conversely, it is possible to effectively suppress disturbances in the playback screen when returning from the special playback state to the normal playback state.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG.
The figure is an explanatory diagram of its operation, and FIG. 3 is a circuit diagram showing a conventional device. In the figure, (1) to (4) are playback heads, (5) is a drum, (6) is a magnetic tape, (7] to αQ are amplifiers,
(c) is the head switching circuit, αG is the still playback command signal,
AnrI'i is a high-speed reproduction command signal, (1) is a video reproduction circuit, clυ is a delay circuit, and □□□ is a delay signal, and the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] It has multiple playback heads installed on a drum that picks up signals recorded on magnetic tape, and during normal playback and still playback, the desired head is selected for playback, and during high-speed playback, all heads are selected for playback. In a magnetic recording/playback device that selects a head and plays back using the head with a larger playback signal output among adjacent heads, the desired head is selected during still playback in response to a still playback command signal or a high-speed playback command signal. A head switching circuit selects all heads during high-speed playback, receives the above-mentioned still playback command signal and high-speed playback command signal, and controls the rising and falling edges of the still playback command signal.
and a delay circuit that derives a delay signal at the falling edge of the high-speed playback command signal, and this delay signal selects all the heads via the head switching circuit, and selects the one of the adjacent heads with the larger playback signal output. A magnetic recording/playback device characterized in that the head is used for playback.