JPH038107A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To decrease the number of video heads which requires six pieces or more heretofore to four pieces by combining a regular recording/reproducing head by an NTSC mode and a PAL and SECAM mode. CONSTITUTION:At the time of regular reproduction, a reproducing signal is obtained by an NTSC main head 1 and a PAL main head 2 in the same way as the time of recording, passes through switching circuits 11, 12, amplified by a recording/reproducing amplifier 6 and outputted from an input/output terminal 7. On the other hand, at the time of reproducing a still picture, first of all, in the case of reproducing a signal of an NTSC system, an NTSC reproducing exclusive head 4 and a PAL main head 2 are used, a phase difference of reproducing signals of each of them becomes a value corresponding to an interval d1 between head gaps, and the interval d1 is set so as to become an integer multiple of a horizontal period at the time of NTSC operation. Therefore, a skew caused by a phase shift of a horizontal signal is not generated in a reproducing signal, and since the PAL main head 2 and the PAL reproducing exclusive head 4 have the same azimuth, a field reproducing still picture for reproducing the same track on a magnetic tape is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device that is capable of recording and reproducing video signals according to a plurality of standard systems such as NTSC, PAL, and SECAM with a single device.

[Conventional technology]

In a magnetic recording/playback device equipped with a rotating head such as a video tape recorder, when playing still images from recorded video signals such as television video signals, the playback image may contain noise due to a mismatch between the recording track and the head trace, or may cause noise peculiar to frame playback. Image blur occurs.

Conventionally, as a method to reduce the above-mentioned noise and image blur, for example, "National Technical Revo-h (Nat.
ional Technical Report)J
, Vol. 28. No, 3. June 1982. p
As described in pages 29 to 32, three-head and four-head configurations with double azimuth gaps were used, and the same track was traced by heads with the same azimuth gap during still image reproduction.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, for example, only one type of NTSC video signal is recorded and played back;
The object of the present invention is to solve the problem that, if one attempts to record and reproduce other systems such as the PAL system and the SECAM system in a single device, six or more sets of heads are required, and the circuit and structure become complicated. solves the problems of the prior art described above.

It is an object of the present invention to provide a magnetic recording/reproducing device which is capable of recording and reproducing video signals of the above-mentioned multiple systems by using only the number of heads required for one system.

[Means to solve the problem]

The above purpose is to install, for example, a double azimuth head for the NTSC system and a double azimuth head for the PAL system or SECAM system at approximately 180 degrees with respect to the rotating drum.
This is achieved by placing the problem in degrees.

[Effect]

During normal recording and playback, the opposing main heads are used in each of the NTSC, PAL, and SECAM modes, and during still image playback, for example, N is used for NTSC video signals.
By tracing and reproducing the same track using an azimuth head exclusively for TSC type reproduction and a PAL head, a still image with less noise and no screen blur can be reproduced.

〔Example〕 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a layout diagram of a video head (hereinafter simply referred to as a head) on a rotating drum to explain one embodiment of a magnetic recording/reproducing apparatus according to the present invention, and 1 is a main head for NTSC video signals (hereinafter simply referred to as a head). (simply referred to as NTSC main head)
, 2 is the main head for PAL video signals (hereinafter simply P
3 is a playback-only head for PAL video signals (hereinafter simply referred to as the PAL playback-only head); 4 is a playback-only head for NTSC video signals (hereinafter simply referred to as the NTSC playback-only head). , 5 is a rotating head drum (hereinafter simply referred to as a rotating drum).

In the figure, the NTSC main head 1 and the NTSC playback-only head 4 constitute a 1st Mi double azimuth video head (hereinafter simply referred to as a double azimuth head), and the PAL main head 3 and the PAL playback-only head constitute a 1st Mi double azimuth video head. It consists of two sets of double azimuth heads, and what is the first set of double azimuth heads?

They are arranged at intervals of approximately 180 degrees on the rotating drum 5,
The NTSC main head 1 and the PAL main head 2 are positioned facing each other at 180 degrees on the rotating drum 5.

Also, what are the NTSC main head 1 and the NTSC read-only head 4 of the first set of double azimuth heads?

The PAL main head 2 and the PAL playback dedicated head 3 of the second set of double azimuth heads are spaced apart by a distance d in the circumferential direction of the rotating drum 5, and the PAL main head 2 and the PAL playback dedicated head 3 are separated by a distance d□ in the circumferential direction of the rotating drum 5.
are placed apart from each other.

FIG. 2 is a schematic block diagram of the recording and reproducing circuit of the magnetic recording and reproducing apparatus according to the present invention, in which 6 is a recording and reproducing amplifier, 7 is an input/output terminal, and 11 to 14 are switching circuits, corresponding to the same parts as in FIG. 1. do.

In the figure, during recording, the luminance signal of the video signal is FM modulated, and the chroma signal is low frequency converted and input to the input/output terminal 7. The input recording signal is amplified to the required level by the recording/reproducing amplifier 6, and then sent to the NTSC signal via 11 and 12.
It reaches the main head 1 and the PAL main head 2, and is recorded on a magnetic tape, which is a recording medium.

Note that here, the NTSC main head 1 has (+) azimuth,
It is assumed that the PAL main head 2 has a (-) azimuth.

The NTSC playback dedicated head 4 has (-) azimuth,
PAL playback exclusive head 3 has (+) azimuth.

During normal playback, the NTSC main head 1 is
A reproduction signal is obtained from the PAL main head 2, and the switching circuit 1
1 and 12, is amplified by a recording/reproducing amplifier 6, and is output from an input/output terminal 7.

On the other hand, during still image playback, unlike the normal playback described above, in the case of NTSC signal playback, by using the NTSC playback dedicated head 4 and the PAL main head 2,
The phase difference between each reproduced signal is 1if between the Herad gaps.
The value corresponds to t d 1.

This interval d□ is set so that the phase difference between the signals is an integral multiple of the horizontal period during NTSC operation.

Therefore, no skew occurs in the reproduced signal due to a horizontal signal phase shift, and the PAL main head 2 and the PAL reproduction-only head 4 have the same azimuth.

Field reproduction still images are obtained by reproducing the same track (field) on the magnetic tape. Compared to frame-reproduced still images, field-reproduced still images have no single-image blur;
There is also less noise.

In the case of PAL signal playback, by using the PAL playback dedicated head: 3 and the NTSC main head 1, the NTSC
As in the case of C4g reproduction, still images with no image blur and little noise can be obtained.

Here, the interval d2 between the PAL main head 2 and the PAL read-only head gap is set to be an integral multiple of the horizontal period during PAL operation.

In addition, although the NTS C system and the PAL system were explained above as examples, the NTS C system and the SECAM system,
Still images with reduced noise and screen blur can be reproduced in the same manner for the PAL and SECAM systems.

〔Effect of the invention〕

As explained above, according to the present invention, one normal recording and reproducing head is used for the NTSC mode, PAL and SECAM mode, and PAL and SECAM mode, thereby reducing the number of video heads that were conventionally required to be six or more. It is possible to reduce the number of magnetic recording devices to four, and to provide a magnetic recording and reproducing device with low device cost.

[Brief explanation of the drawing]

FIG. 1 is a head layout diagram according to an embodiment of the present invention. FIG. 2 is a schematic block diagram of the recording/reproducing circuit. 1.NTSC main head, 2..PAL main head. 3. PAL playback exclusive end, 4. NTSC playback head, 5. Rotating drum. 1st item 2nd item I+

Claims (1)

[Claims] 1. In a magnetic recording and reproducing device equipped with two sets of double azimuth video heads arranged at an interval of approximately 180 degrees on a rotating head drum, the distance between the gaps of the double azimuth video heads is determined by the two sets of double azimuth video heads. A magnetic recording/reproducing device characterized by different features.