JPS6157186A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To avoid a production of an ugly noise bar during a particular reproducing mode by fixing a reproduced luminance signal level obtained from a demodulator to a fixed luminance level when a detecting level of a reproducing output does not reach a reference level. CONSTITUTION:In case of reproducing, a tape recorded at a standard mode at a particular reproducing mode, since a video head 1 does not trace a recording track correctly, a detecting level of an envelope detector 4 is lowered remarkably and lower than a reference voltage level and during this time, a comparison output of a level comparator 5 goes to level. At this time, an AND gate 8 is opened, and a horizontal synchronous signal is fed to a horizontal synchronous signal addition device 9 from a horizontal synchronous signal generator 6. Namely, during a period of a noise bar appearing on a receiver, a reproduced luminance signal obtained by an FM demodulator 3 is fixed to a fixed luminance level by a luminance level fixing device 7 and further the horizontal synchronous signal is added to a luminance signal level by the adder 9 and outputted.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a magnetic recording and reproducing device using the Heli-force/L/Nu-can method that is capable of special reproduction such as fast-forward playback, rewind playback, still image playback, and slow-motion playback. be.

<Prior art and problems> Generally, in this type of magnetic recording/reproducing device, a noise bar appears on the screen of the monitor receiver during special playback mode, but this noise bar has a range from white level to black level/L.
/, and this noise bar becomes very unsightly, especially when a tape recorded in standard mode with sufficient guard bands between tracks is played back in such special playback mode. .

<Objective of the Invention> Accordingly, the present invention provides a magnetic recording and reproducing apparatus in which unsightly noise bars do not appear during special reproduction mode.

Further, the present invention provides a magnetic recording and reproducing apparatus that does not cause horizontal synchronization disturbance during special reproduction mode.

Embodiments> The present invention will be described below according to embodiments shown in the drawings. The drawing shows an embodiment of the present invention, particularly a block diagram of a playback system related to the present invention, where 1 indicates a video head;
2 is a reproduction amplifier for amplifying the reproduction output reproduced by the video head 1; 3 is an FM demodulator for FM demodulating the signal amplified by the reproduction amplifier 2 to obtain a reproduction luminance signal; 4;
5 is an envelope detector for detecting the signal level of the signal obtained from the regenerative amplifier 2; 5 is a comparator that compares the detection level /L/ detected by the detector 4 with a certain reference voltage level; A horizontal synchronizing signal generator 7 generates a horizontal synchronizing signal based on the comparative output of the comparator 5, especially when the detection level of the detector 4 does not reach the reference level, the reproduced luminance signal from the FM demodulator 3 is detected. A brightness level fixer 8 fixes the level to a constant brightness level, and 8 is the same as the detector 4.
An AND gate 9 gates the horizontal synchronizing signal generated from the level signal generator 6; It is a synchronous signal adder.

In a magnetic recording and reproducing device composed of the above,
In normal playback mode, the signal detection level of the envelope detector 4 is always higher than the reference voltage, so
The comparison output of the level comparator 5 is at the "L" level. Therefore, the AND gate 8 remains closed and neither the brightness level fixer 7 nor the horizontal synchronizing signal adder 9 operates, and in this case, the reproduced brightness signal demodulated by the FM demodulator 3 is transferred to the level fixer 7 and the signal It is outputted as it is through the adder 9.

However, when in a special playback mode such as fast forward playback or rewind playback, especially when a tape recorded in the standard mode is played back in such a special playback mode, the video head 1 will not be able to reproduce the information recorded on the magnetic tape. Because it does not trace the track exactly, but across multiple gartbands,
At this time, the detection level of the envelope detector 4 drops significantly and is even lower than the reference voltage level, during which the comparison output of the level comparator 5 becomes "H" level.Therefore, at this time, the AND gate 8 is opened and the level A horizontal synchronizing signal is supplied from the synchronizing signal generator 6 to the horizontal synchronizing signal adder 9 via the AND gate 8.As a result, every time the output level of the level comparator 5 becomes "H", that is, the monitor image is During the period in which a noise bar appears on the machine, the reproduced brightness signal obtained from the FM demodulator 3 is fixed at a constant brightness level by the brightness level fixer 7, and further adjusted to this brightness signal level by the horizontal synchronization signal adder 9. A horizontal synchronizing signal will be added and output.

When the reproduced luminance signal obtained in this manner is supplied to a monitor receiver, the noise bar on the monitor screen is suppressed to a predetermined luminance level or less, making it unnoticeable, and no disturbance of horizontal synchronization occurs during this time.

<Effects> As described above, according to the magnetic recording and reproducing apparatus of the present invention, there is no unsightly noise bar in the special reproduction mode as in the conventional case, and no synchronization disturbance occurs.

[Brief explanation of the drawing]

The drawing is a block diagram of one embodiment of the present invention. 1... Video head, 2... Regenerative amplifier, 3.
...FM demodulator, 4...Envelope detector,
5... Level comparator, 6... Horizontal synchronizing signal generator, 7... Brightness level fixer, 8... AND gate, 9... Horizontal synchronizing signal adder.

Claims (1)

[Claims] 1. A reproduction amplification means for amplifying the reproduction output of a video head in a helical scan type magnetic recording and reproduction device capable of special reproduction such as fast forward reproduction, rewind reproduction, still image reproduction, and slow motion reproduction. FM demodulation means for FM demodulating the output signal from the amplification means to obtain a reproduced luminance signal; level detection means for detecting the level of the output signal from the amplification means; and level fixing means for fixing the level of the reproduced luminance signal obtained from the demodulating means to a constant luminance level when the detection level does not reach the reference level based on the comparison output from the comparing means. A magnetic recording and reproducing device characterized in that a noise bar is made inconspicuous during a special reproduction mode. 2. In a helical scan type magnetic recording and reproducing device capable of special reproduction such as fast-forward playback, rewind playback, still image playback, and slow motion playback, a playback amplification means for amplifying the playback output of a video head; FM demodulation means for FM demodulating the output signal of and obtaining a reproduced luminance signal;
level detection means for detecting the level of the output signal from the amplification means; level comparison means for comparing the detection level by the detection means with a reference level; and the detection level reaching the reference level based on a comparison output from the comparison means. level fixing means for fixing the level of the reproduced luminance signal obtained from the demodulating means to a constant luminance level when the detected level does not reach a reference level; What is claimed is: 1. A magnetic recording and reproducing device comprising means for adding a horizontal synchronizing signal to prevent synchronization disturbance during special reproduction mode.