JP2822188B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type magnetic recording / reproducing apparatus capable of recording or reproducing information on or from a magnetic tape by a rotating head. .

[Summary of the Invention]

The magnetic recording / reproducing apparatus of the present invention includes, for example, N rotating heads for recording a video signal and the like, and is formed on a magnetic tape by a rotating drum whose rotation speed corresponds to the field period of the video signal. When scanning a track pattern, the number of rotations of the rotating drum is set to, for example, twice, and at the same time, the time axis of the recording signal supplied to the rotating drum is compressed by half, and the number of rotating heads required Is halved. For this reason, it is not necessary to adjust the variation between the conventional plurality of rotary heads, and it is possible to reduce the number of stages of the rotary transformer, reduce crosstalk between the recording and reproducing systems, and the like.

[Conventional technology]

A helical scan type recording / reproducing device (VTR) that records and reproduces information on a track inclined with respect to the longitudinal direction of the tape by a magnetic head mounted on a rotating drum is usually used for recording and reproducing composite video signals. Although suitable, but when a higher quality video signal is required, the component video signal is recorded / reproduced.

FIG. 5 shows an example of a rotating drum widely used as a high-quality VTR for a broadcasting station. Y _A (P) and Y _B (P) arranged at an angle of 180 ° are luminance signals. , _A pair of heads for reproducing color signals, C _A (P) and C _B (P), similarly indicate a pair of heads for reproducing color signals, and include Y _A (P), C _A (P) and
Y _B (P) and C _B (P) are respectively Peaheddo having a predetermined step.

Similarly, Y _A (R) · C _A (R) and Y _B (R) · C
_B (R) is also configured in the same manner as the pair head for reproduction, and shows a recording head for recording a luminance signal and a chrominance signal. These recording pair heads are almost the same as the reproduction pair head. They are arranged in orthogonal directions.

The rotating head drum D as described above is normally driven to rotate once so as to make one rotation in one frame of a video signal. For example, in the case of an NTSC color video signal, the number of rotations is 1800 r. pm.

As shown in FIG. 6, the tape wound around the rotary drum so as to have a wrap angle of about 180 ° has tracks Y _A , C _A ,
Y _B and C _B are sequentially formed.

A luminance signal Y of the first field of Y _A to track the C _A color video signal, the color signal C is recorded, the next
A luminance signal Y and a chrominance signal C of the second field are recorded in Y _B and C _B.

The luminance signal Y is a real-time luminance signal recorded as shown in FIG. 7, while the color signal C is a color difference signal RY and a BY signal.
Each component is recorded with its time axis compressed to half.

FIG. 8 shows a recording system for supplying a signal to the head having the drum structure for recording, and a recording / reproducing system for reproducing a signal from the head.
A block diagram of a reproduction system is shown. Reference numerals 1 and 6 denote emphasis circuits for a luminance signal Y and a chrominance signal C. Reference numerals 2 and 7 denote FM modulation circuits for a luminance signal and a chrominance signal. The circuits, 4A, 4B, 9A, 9B, are recording amplifiers, and 5 is a recording rotary transformer.

Reference numeral 10 denotes a color signal system digital signal processing circuit. The color difference signals RY and BY are converted into digital signals by A / D converters 11R and 11B, respectively.

Then, the data is written to the field memories 12R and 12B. At the time of reading, the time axis is compressed to 1/2 by doubling the read clock of the field memories 12R and 12B. By switching with the switch 13, a time-division color signal C is formed as shown in FIG. 7, and the D / A converter 14 converts the signal into an analog signal again.

Head for recording at the time of reproduction _{[Y A (R), Y B} (R), C
_{A (R), C B (} R) ] in recorded four heads for reproduction from the recording track _{[Y A (P), Y B} (P), C A (P), C
_B (P)] reproduces a video signal.

21A, 21B and 28A, 28B are luminance signal and color signal reproduction amplifiers, 22 is a reproduction rotary transformer, 23, 24 are reproduction head switching circuits, and 25Y, 26Y, 27Y are reproduced luminance signal equalizers. , A demodulation circuit, and a de-emphasis circuit. Reference numerals 25C, 26C, and 27C denote an equalizer, a demodulation circuit, and a de-emphasis circuit for a reproduced color signal.

Reference numeral 30 denotes a digital signal processing circuit of a reproduction system, and a luminance signal is transmitted to a field memory (TB) via an A / D converter 31Y.
C) Written to 33Y, where after compensating the time axis, D /
It is output via the Y converter 34Y.

Similarly, the color signal is also input to the A / D converter 31C, and the RY signal data and the BY signal data are switched by the switch 32 and written into the field memories 33R and 33B, respectively.

The field memories 33R and 33B are for returning the color signal, which has been time-axis-compressed in half by the read clock, to the original time-axis.
And BY signals are converted into analog signals by D / A converters 34R and 34B.

Such a recording method of a video signal is a so-called Y / C separation recording method because a luminance signal Y and a color signal C compressed on a time axis are respectively recorded on different tracks. High image quality can be achieved without causing distortion due to intermodulation of the carrier of the luminance signal Y and the carrier of the color signal C.

[Problems to be solved by the invention]

However, since the number of heads mounted on the rotary head is larger than that of a normal VTR system, there is a problem that the number of stages of the rotary transformer is increased (eight stages), and at the same time, the characteristics of a pair of heads vary. If there is, the image quality is degraded by recording / reproduction, and particularly, field flicker occurs. Therefore, there is a problem that adjustment and compensation of the azimuth angle and sensitivity of the pair head are required.
Also, in particular, if a reproducing system head is a DT head (dynamic head) for scanning a track accurately, there is a problem that the price increases as the number of heads increases.

Further, when a system that simultaneously performs recording and reproduction is adopted, both heads come into contact with the tape at the same time, so crosstalk occurs in the recording-reproduction system. There is also a problem that the cost is increased.

[Means for solving the problem]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and it is necessary to increase the number of rotations of a rotating drum by compressing a time axis of a color video signal to be recorded, and as a result, to mount on a rotating drum. The number of heads can be halved.

[Action]

In recent years, the recording / reproducing characteristics of magnetic tapes and the performance of magnetic heads have been remarkably improved, so that signals of extremely high frequencies (several tens of MHz) can be recorded and reproduced.

Therefore, in the case of the helical scan type recording / reproducing apparatus of the present invention, utilizing the improvement of the recording / reproducing function,
The frequency / time axis of the recorded information is compressed to 1/2 to obtain a higher frequency than the conventional one, and the number of rotations of the rotating drum is set to twice. As a result, the number of rotating heads required is
It can be.

Compatibility is ensured by configuring so that recording / reproduction can be performed in the same format as the recording pattern of the conventional two-channel VTR.

〔Example〕

Figure 1 is shows a plan view of a rotary drum D showing an embodiment of the present invention, Y A _{· B (P)} and C _{A · B (P)}
Each luminance signal Y, and the reproducing Peaheddo for reproducing the color signals _{C, Y A · B (R} ) · C A · B (R) is the reproducing head _{Y A · B (P) ·} C A · _B (P) and 180
The recording pair heads facing each other at an angle of 示 す are shown.

These paired heads are arranged with a height difference of one track in the height direction of the drum, and the head for the luminance signal and the head for the chrominance signal are formed at different azimuth angles.

The rotation speed of the rotating drum D is twice that of the conventional VTR (3600 rpm in the NTSC system). In the case of the rotating drum having the same diameter D as the conventional VTR, the tape T has a wrap angle of approximately 180 ° + α. Can be wound on a rotating drum.

The luminance signal Y to be recorded is supplied by compressing the time axis of the signal to 1/2, and the color signal to be recorded is the color difference signal RY as shown in FIG. , BY
The components are supplied in a time-sharing manner within one horizontal period.

Then, these signal components (RY) and (BY)
Are compressed so that the time axis becomes 1/4.

One embodiment of the helical scan type recording / reproducing apparatus of the present invention has a drum structure as described above.
As described below, the same pattern as the tape recording pattern by the conventional rotating drum of one rotation per frame can be used.

First, in the case of the conventional rotating drum (FIG. 5), the traveling direction of the tape T is the direction indicated by the arrow X as shown in FIG. when moving in an oblique direction, the progression of the tape T is stopped, the scanning trace of the rotary head in this case is as shown by a chain line, it is set by the inclination angle theta ₀ of the rotating drum and the tape T.

When the tape T in this state is moved at a velocity v, in the case of conventional, the trajectory of the rotary head for recording the inclination theta ₁ as shown a solid line, and a dotted line.

Solid lines indicate the trajectories of the rotary heads Y _A (R) and Y _B (R) of the luminance signal, and dotted lines indicate the rotary heads C _A (R) and C of the color signal.
_This is the locus of _B (R).

Then, the rotary heads Y _A (R), C _A (R) and Y _B (R), C _B
The track interval of (R) is v / F, that is, the running distance (d) of the tape that advances in one field.

By the way, since the rotation speed of the recording head according to the embodiment of the present invention is twice as high as that of the conventional one, when the speed v of the tape is the same, the track locus is θ _{2 as} shown by a two-dot chain line. . Then, 2T _Y becomes the locus of the rotary head Y _{A · B (R)} for the luminance signal, 2T _C is the locus of the rotary head C _{A · B (R)} of the color signal.

Therefore, although the track pattern has a different angle from the conventional track pattern by θ ₁ −θ ₂ , the track pitch can be the same.

Therefore, in the case of the present invention, if the inclination angle between the rotating drum and the tape is increased by θ ₁ −θ ₂ in advance, the track pattern formed by the conventional rotating drum of 1800 rpm and the double rotation speed can be obtained. The inclination of the recording track pattern by the rotating drum, which is set to 3600 rpm, matches.

Next, in the case of the embodiment of the present invention, since the rotation speed is doubled, the relative speed with respect to the tape is also almost 2 times.
Double.

Therefore, the frequency and time axes of the luminance signal and the chrominance signal to be supplied to the recording heads YA _{/ B} (R) and CA _{/ B} (R) are compressed and supplied to 1/2, thereby recording on the conventional tape. The signal density can be the same as the signal density.

That is, the signal density of the conventional track indicated by the mark ○ and the signal density of the track according to the method of the present invention indicated by the mark △ can be the same.

The tape speed v of the recording / reproducing method according to the method of the present invention is the same as that of the conventional recording / reproducing method.

Therefore, when the recording / reproducing method of the present invention is adopted, a slight change in the number of rotations of the drum and the inclination angle of the tape causes
The same recording pattern can be obtained with half the number of heads in the related art, and compatibility can be maintained.

The diameter r of the rotating drum can be arbitrarily selected by changing the wrap angle of the tape wound around the drum, and the difference in recording track length is small. Can be absorbed.

FIG. 3 is a block diagram of a component recording / reproducing system according to the present invention, and the same symbols as those of the conventional recording / reproducing system block in FIG. 8 indicate the same functional parts.

As can be understood from this block diagram, in the case of the recording / reproducing method of the present invention, the head changeover switches 3, 8, 23, and 24 are omitted, and the number of stages of the rotary transformer, the number of recording amplifiers, and the number of recording heads are halved. I have.

In the luminance signal and the color difference signal is a digital signal processing circuit 40, the time axis, respectively, are outputted after being compressed, the luminance signal is A / D converters 41Y, 4f _s (f _sc is the subcarrier frequency) are sampled at After being converted to a digital signal, the signal is supplied to the memory 42Y, and then read out at 8 _fs , whereby the time axis is compressed by half, and the time axis is compressed by the D / A converter 44Y to an analog signal. Has been converted.

The color difference signals RY and BY are output from the A / D converters 41R and 41B, respectively.
Is sampled by the clock of 2f _sc , and the memory 42R,
Supplied to 42B. Then, the time axis by being read by the 8f _sc clock is compressed to 1/4 is output as R-Y, divided color signal when the B-Y as shown in FIG. 7 via the switch 43, D It is converted to an analog signal in the / A converter 44C.

Therefore, as compared with the conventional component recording / reproducing method, the luminance signal and the chrominance signal are subjected to emphasis in a higher frequency band than the conventional one because the time axis is compressed to 1/2. Then, the modulation frequencies of the FM modulators 2 and 6 are also set high. FM modulated luminance signal, and the color signal head for recording via the rotary transformer 5 in two stages is fed continuously to the _{(Y A · B (R)} , C A · B (R)).

In the reproducing system of the block of the present invention (PB), the recording head _{(Y A · B (R)} , C A · B (R)) signal recorded by the head for reproduction _{(Y A ·} B ₍ P), C _AB
(P)). The reproduced luminance signal and chrominance signal are supplied to demodulation circuits 26Y and 26C via equalizers 25Y and 25C, and de-emphasis circuits 27Y and 27C.
After compensating frequency characteristics with 7C, digital signal processing circuit
Entered in 50.

It reproduced luminance signal input to the digital signal processing circuit 50, A / D converter for sampling the clock of 8f _sc 51Y
, And supplied to the memory 53Y.

Then, the luminance signal of one field recorded in the memory 53Y is read out by the clock of 4 _fs , whereby the time axis is doubled, and then output through the D / A converter 54Y to be executed. A time luminance signal is output.

The color signal component is converted into a digital signal by an A / D converter 51C, which samples the signal with a clock of 8 _fsc , and then separated by a switch 52 into color difference signals RY and BY.

The separated color difference signals RY and BY are written into the memories 53R and 53B, respectively, and then read out by a clock (2f _sc ) having a quarter of the write clock, thereby increasing the time axis to four times. Is done.

By controlling the read timing of the memories 53R and 53B, the real-time color difference signals RY and BY signals having the same phase are output to the D / A converters 54R and 54B.

As described above, in the case of the recording / reproducing method of the present invention, since the number of rotating heads is halved compared to the conventional one, the recording / reproducing characteristics of each field become uniform, and the conventional 180 ° facing type head is used. In this case, the head changeover switch can be omitted.

Further, since the number of conversion stages of the rotary transformer can be reduced to half, the size of the transformer device can be reduced, and the effect of improvement in terms of crosstalk can be increased.

FIG. 4 shows an embodiment in which the rotary head structure of FIG. 1 is modified.

In the case of this embodiment, a recording head Y for recording a luminance signal
_AB (R) and head for reproducing the luminance signal Y _AB (P)
There was opposed 180 ° angle, then head _{Y A · B (R),} Y A · B recording head for color signals in the direction perpendicular to the _{(P) C A · B (} R for the luminance signal ) and the read head _{C a · B}
(P) is provided.

Heads Y _AB (R) and Y for luminance signal
_AB (P) and color signal heads CA _AB (R), C
_AB (P) is set to a predetermined head height so that a conventional recording pattern can be formed when the number of rotations of the drum is doubled, and the recording and reproduction can be performed simultaneously. a recording head Y _{a · B} of the luminance signal _(R), reproducing heads Y _{a · B (P)} is preferably configured to scan the same track.

If necessary, a magnetic head for erasing can be provided. In this case, the angle between the recording head and the reproducing head is preferably set in consideration of the balance of the rotating head.

In the above embodiment, the Y / C separation recording / reproducing system is described as an embodiment. However, at least a video signal for one frame is recorded and reproduced by two or more opposing rotating heads, and the VTR is also reproduced. By applying the recording / reproducing method of the present invention, the number of magnetic heads can be halved in the same tape format, and variations in the recording / reproducing characteristics of the head can be eliminated.

〔The invention's effect〕

As described above, the magnetic recording / reproducing apparatus of the present invention can scan a track pattern formatted by the conventional helical scan method by at least half of the rotating head, thereby achieving a significant cost reduction. This has the effect.

In addition, there is an advantage that the number of stages of the rotary transformer is reduced by half, and the occurrence of crosstalk during simultaneous recording and reproduction can be prevented by proper arrangement of the rotary head.

[Brief description of the drawings]

FIG. 1 is a layout view of a rotary head showing one embodiment of the present invention,
FIG. 2 is an explanatory view of a track pattern corresponding to the peripheral speed of the rotary drum, FIG. 3 is a block diagram showing an embodiment of a recording / reproducing system circuit in the magnetic recording / reproducing apparatus of the present invention, and FIG. Of another embodiment of the rotary head of FIG.
FIG. 6 is a layout diagram showing an example of a conventional rotary head, FIG. 6 is an explanatory diagram of a track pattern formed by the rotary head shown in FIG. 5, FIG. 7 is a waveform diagram of a recording signal, and FIG. FIG. 2 is a block diagram of the magnetic recording / reproducing apparatus of FIG. In the figure, Y _AB (R) is a head for recording a luminance signal, C
_{A ·} B (R) is a recording head of a color _{signal, Y A ·} B (P)
Denotes a head for reproducing a luminance signal, _{and CAB} (P) denotes a head for reproducing a chrominance signal.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) G11B 5/008 G11B 5/02 H04N 5/92 H04N 9/80

Claims (1)

(57) [Claims] An inclination angle θ of a recording track is θ with respect to a rotation drum having N rotation heads and a peripheral speed of V.
In a magnetic recording / reproducing apparatus of a helical scan type in which a magnetic tape is caused to run against a magnetic tape so as to be 1, when n is an integer of 2 or more, the peripheral speed of the rotary drum is nV, and The time axis compression ratio of the supplied recording signal is 1 / n, and the number of rotating heads mounted on the rotating drum is N / n
Wherein the angle of the abutting surface between the rotary drum and the magnetic tape is set so that the inclination angle of the recording track of the magnetic tape becomes the θ1. Playback device.