JPH07134818A - Magnetic recording/reproducing apparatus - Google Patents

Abstract

PURPOSE:To obtain a high density recording VTR by controlling the relationship in a relative position of scanning of a magnetic head so that a reproducing time interval of a tracking signal is a value proportional to a recording time of the tracking signal. CONSTITUTION:A reproduction output of a tracking signal reproducing head is amplified by a reproducing amplifier 23 and inputted to a tracking signal reproducing time width error detecting circuit 24. The circuit 24 detects a reproducing interval time axis error of a tracking signal and inputs a signal of this error to a head relative height control circuit 25. The circuit 25 changes the relative height of a head base whereon a tracking signal reproducing magnetic head 18 and a video signal reproducing head 19 are mounted, so that the error signal fed back be zero. According to this constitution, the linearity of a recording track is improved and VTR of which the width of the recording track is 5mum or below is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder (VTR) for recording and reproducing color video information such as moving images and still images, audio information, character information and various data at high density on a magnetic recording medium such as a magnetic tape. Abbreviated) and the like.

[0002]

2. Description of the Related Art Conventionally, at home, a VHS such as a VHS system or an 8 mm system is used as a VTR for recording a color video signal.
TR is widely used. Especially, VHS system VTR
About 250 million units have been spread all over the world, and they are widely used at home on a daily basis. In these VTRs, for example, an input NTSC color video signal is separated into a luminance signal and a carrier color signal, the luminance signal is frequency-modulated with a low carrier, and the carrier color signal is converted into a low frequency band and recorded on a magnetic tape. ing. The recording / reproducing system is described in, for example, Yokoyama, “Home Video Technology,” edited by Japan Broadcasting Corporation and Sugaya, SMPTE Journal, March 1986, pages 301 to 309.

[0003]

However, at the present time,
These conventional VTRs have problems in their low recording density. In other words, due to the improved tape performance of metal vapor deposition tapes and metal-coated tapes in recent years,
As a reproducing signal-to-noise ratio of the tape head system, recording / reproducing has become sufficiently practical even if the head track width is 5 μm. However, in the VHS system or the 8 mm system VTR described above, the linearity in which the head scans the track at the time of recording and reproducing is poor. For example, when the track width is set to 5 μm in order to increase the recording time, There is a problem that the reproduction output is reduced by 10 dB or more during the compatible reproduction between the decks and the reproduction becomes impossible. That is, no VTR has a track width of less than 10 μm, and breakthrough is necessary to reduce the track width to 5 μm or less.

On the other hand, in a hard disk which is a peripheral device such as a computer, a high density has been rapidly developed in recent years, and a track density of 5 μm or less has been realized by using an optical servo technique.

In view of the above points, the present invention has an object to provide a VTR having a track width of 5 μm or less.

[0006]

In order to achieve the above object, the present invention comprises means for forming a plurality of tracking signal tracks in a direction perpendicular to the width direction of a magnetic tape and a means arranged on the circumference of a rotating cylinder. A first magnetic head for reproducing the tracking signal, a second magnetic head arranged on the circumference of the rotary cylinder for recording or reproducing a signal inputted from the outside, and a rotary cylinder for rotating the rotary cylinder. A configuration including a motor and a control circuit that controls a relative positional relationship in which the magnetic head scans the tape so that the reproduction time interval of the reproduced tracking signal becomes a value proportional to the recording interval of the tracking signal. Is.

[0007]

According to the present invention having the above-mentioned structure, before recording a video signal, an audio signal or the like on the magnetic tape by the head on the rotating cylinder, the magnetic tape is parallel to the direction perpendicular to the width direction of the magnetic tape, that is, the tape running direction. In this direction, a plurality of tracking signal tracks are recorded at equal intervals. At the time of recording the external input signal, these tracking signals are reproduced by the tracking signal reproducing head on the rotary cylinder, and the time axis error from the expected value of the reproduction time interval of the tracking signal is detected.

Generally, in a VTR, the linearity when the head helically scans the tape is unique to the deck and the tape used. Therefore, once the time base error is detected for a certain deck and tape, there is almost no change in linearity except that due to temperature change. Therefore, by feeding back this error component to, for example, head relative height control, rotation cylinder rotation control, tape drive capstan motor control, etc., the linearity of the tape scanning of the head can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In the present embodiment, a case where the present VHS system VTR is applied will be described.

FIG. 1 comprises a signal processing section 1 and a tape / head section 2. In the signal processing unit 1, NT
The SC composite video signal is input from the input terminal 3, and the recording side video signal processing circuit 4 performs recording signal processing. That is, first, the NTSC composite video signal is separated into a luminance signal and a carrier color signal, and then the luminance signal is subjected to emphasis and then FM modulation. Further, the carrier color signal is low-pass converted to the low frequency region, and then the FM modulated color signal and the low-pass converted color signal are added. Then, the added signal is amplified to a recording signal level by the recording amplifier 5 and transmitted to the magnetic head 19 (and 33) on the rotating cylinder shown in FIG.

The recording side signal processing circuit 4 also outputs a tape running mode identification signal indicating whether the recording mode is the standard mode or the long time mode, to the tracking signal generating circuit 6.
Output to. The tracking signal generation circuit 5 keeps the recording wavelength of the tracking signal always 5 μm even if the running speed of the magnetic tape 8 changes, so that each tracking signal recording head 10 on the tracking signal recording head array 9
Controls the frequency of the output signals of 11, 12, 13, 14, 15 and 16.

For example, in the standard mode of the VHS system, the tape running speed is about 33.3 mm / sec, so the recording frequency of the tracking signal is about 6.7 kHz. Also, V
The tape running speed is approximately 1 per second in the HS system long time mode.
Since it is 1.1 mm, the recording frequency of the tracking signal is about 2.2 kHz. In the present embodiment, the recording wavelength of the tracking signal is set to 5 μm, which has a relatively high reproduction output, but it may be another frequency or the recording frequency may be changed for each track.

The tracking signal is erased by overwrite by the video signal recording head, but only about 20 dB is erased by the well-known deep recording principle, and a part of the tracking signal remains on the tape. To do. Since the tracking signal in this embodiment is a single wave, it is possible to extract a tracking signal carrier with a high SN ratio by using a band pass filter (BPF) during reproduction, and it can be used as a high precision tracking control signal for the magnetic head. . Further, the tracking signal and the video signal can be band-shared by changing the recording azimuth on the track.

The tracking signal recording head array 9 is arranged between the full erase head (not shown) and the rotary cylinder in the traveling path of the magnetic tape 8. Further, the tracking signal recording heads 10, 11, 1
2, 13, 14, 15 and 16 are arranged on the tracking signal recording head array 9 in the width direction of the magnetic tape 8 at equal intervals with a high precision on the order of μm, and the head track width of each tracking signal recording head is high. Is 10
The μm and azimuth angle are about 25 degrees. With respect to the arrangement accuracy of each tracking signal recording head, since the adjustment accuracy of the head relative height of 1 μm or less has been achieved in the rotary cylinder system such as the conventional VHS system, the relative position adjustment on the submicron order is possible. Further, it is possible to adjust with higher accuracy by laser irradiation or the like.

Each tracking signal recording head 10, 1
The tracks recorded by 1, 12, 13, 14, 15 and 16 are respectively recorded as TR1, TR2, TR3 and TR.
4, TR5, TR6 and TR7. The intervals between the tracking signal recording tracks are formed with high accuracy and uniformly.

The magnetic tape 8 is running in the direction of arrow 17. Further, a tracking signal reproducing head 18 as a first magnetic head and a video signal recording / reproducing head 19 as a second magnetic head on the rotating cylinder are respectively provided.
It is moving in the direction of arrow 20, which is the scanning direction of the magnetic head. The signal track recorded by the video signal recording / reproducing head 19 is T (+), and the signal track recorded by the magnetic head disposed on the circumference of the rotating cylinder about 180 degrees away from the magnetic head 18 is T (+). -).

When recording a video signal, first,
The tracking signal reproducing head 18 traverses each of the tracking signal recording tracks TR1 to TR7 on the magnetic tape 8 at a relative speed of 5.8 m / s to obtain a tracking signal of a recording wavelength of 1 μm, that is, a tracking signal of 5.8 MHz. It is reproduced and amplified by the reproduction amplifier 23. Since each tracking signal is recorded on the magnetic tape 8 at equal intervals, the reproduction time intervals of each tracking signal should be equal.

However, in the VTR, the linearity when the head scans the magnetic tape 8 is not perfect due to the accumulation of the assembly error of the mechanical system, and the magnetic head moves from end to end of the track. The deviation of linearity due to track bending is about 10 μm in pp value. Normally, if the track bend is so large, the recording track width is set to 1
Since the track cannot be narrowed to 0 μm or less, the recording density cannot be increased. That is, although the recording should have been performed so that the reproduction time intervals of the respective tracking signals are equal, the reproduction time interval changes due to the occurrence of track bending.

Therefore, in this embodiment, attention is paid to the tracking signal reproduction time interval of the tracking signal reproduction head 18, and feedback control is applied to the relative height of the magnetic head so that the tracking signal reproduction time interval becomes constant. , The linearity when the rotary magnetic head scans the magnetic tape is dramatically improved. Generally, when the VTR deck and the tape to be used are determined, the track bending state is also fixed. Therefore, the feedback control synchronized with the rotation of the cylinder may be performed for the track bending given in a similar shape. Further, in general, the track bend has a maximum of 2 to 3 cycles, so that 7 or more detection points of the track bend are sufficient according to the sampling theorem.

In FIG. 1, the reproduction output of the tracking signal reproduction head is amplified by the reproduction amplifier 23 and input to the tracking signal reproduction time axis error detection circuit 24.
The tracking signal reproduction time axis error detection circuit 24 detects the reproduction interval time axis error of the tracking signal. This error signal is input to the head relative height control circuit 25, and the relative height of the head base on which the tracking signal reproducing magnetic head 18 and the video signal recording / reproducing head 19 are mounted is changed so that the error signal fed back becomes zero. Let The control of the relative height can be easily realized by utilizing a well-known technique such as a piezoelectric element.

As described above, since the linearity of the recording track pattern at the time of recording the video signal can be dramatically increased to the order of μm, narrow track recording becomes possible and the density can be increased. When the recording deck and the playback deck are different, the track bending pattern spreads infinitely. Generally, in order to achieve high density by narrowing the track, it is very important to increase the linearity of the recording track from the time of recording. Is important to.

The operation of the tracking signal reproducing head 18 during reproduction is basically the same as that during recording,
The tracking of the video signal recording / reproducing head 19 does not deviate from the reproduction signal track. Video signal recording / playback head 19
After being amplified by the reproduction amplifier 21, the reproduction output of is subjected to signal processing opposite to that of the recording side video signal processing circuit 4 in the reproduction side video signal processing circuit 22, and becomes a composite video signal again from the output terminal 26. Is output.

Now, for a deeper understanding of the present invention, the structure of the tape / head portion of this embodiment will be described with reference to FIG. In FIG. 2, the magnetic tape 8 is wound around the circumference of the rotary cylinder 27 at an angle of about 180 degrees and is supported by fixed posts 28 and 29. The capstan motor 30 and the pinch roller 31 sandwich the magnetic tape 8 and run the magnetic tape 8 in the direction of arrow 17.

Tracking signal reproducing heads 18 and 32 and video signal heads 19 and 33 are mounted on the circumference of the rotary cylinder 27 symmetrically with respect to the center of rotation, and the rotary cylinder is indicated by the arrow 34. The tracks T (+) and T (-) shown in FIG. 1 are scanned on the magnetic tape 8 as it rotates in the direction.

Further, the tracking signal reproducing head 18
The video signal recording / reproducing head 19 is mounted on the head base 35, and the relative height of the video signal recording / reproducing head 19 is changed in the vertical direction 37 by expansion and contraction of the piezoelectric element 36. Similarly, the tracking signal reproducing head 32 and the video signal recording / reproducing head 33 are mounted on the head base 38, and their relative heights are changed in the vertical direction 40 by the expansion and contraction of the piezoelectric element 39. Expansion and contraction of these piezoelectric elements is controlled by the head relative height control circuit 25 described in FIG.
With the above configuration, the magnetic heads 18, 19, 32 and 3
The track locus by which 3 scans the magnetic tape 8 has a very high linearity.

The effectiveness of the present invention will be described with reference to FIG. In FIG. 3A, TR3 and TR4 are tracks recorded by the tracking signal recording heads 12 and 13 which are fixed heads, respectively. TR
The track width Wtr of 3 and TR4 is 10 μm, and the track-to-track distance WB is 1500 μm. A track 41 is a scanning locus of the tracking signal reproducing head 18,
In the HS system, since the track inclination angle θ is 5 degrees 59 minutes, the distance WL between the point A3 that intersects the track 41 at the track end of TR3 and the point A4 that intersects the track 41 at the track end of TR4. Is about 1439 μm (150
0 μm / sin (5 degrees 59 minutes)). Therefore, the time TL for the tracking signal reproducing head 18 to scan from A3 to A4 is about 248 μsec (1439 μm / 5.
8 (m / sec)).

In FIG. 3B, the horizontal axis represents time and the vertical axis represents the output of the tracking signal reproducing head. When the tracking signal reproducing head 18 crosses A3 and A4, the reproduction output becomes maximum values C3 and C4. Here, the tracking signal reproducing head 1
It is assumed that the scanning track of 8 is bent and the intersection with TR4 is shifted to the right by 5 μm from the original position. Then, the time required to obtain the maximum value C4 of the reproduction output is 0.86 μsec (24
Since it is delayed by 8 × 5/1439), the tracking shift amount can be detected by detecting this delay time.

Similarly, the tracking signal reproducing head 1
It is assumed that the scanning tracks of 8 are bent and the intersection with TR4 is displaced to the right by 1 μm from the original position. Then, the time for obtaining the maximum value C4 of the reproduction output is delayed by 170 nsec. With the recent development of digital signal processing, a circuit having a circuit clock frequency of about 50 MHz, that is, a sampling cycle of about 20 nsec can be easily constructed. An actual control circuit can be realized by calculating the track bending state from the track deviation value at the sampling point, further calculating data for correcting the track linearly, and performing feedback control.

As described above, in this embodiment, the tracking deviation can be corrected to about 0.3 μm by the calculation of ((20 × 2) / 170) related to the sampling theorem. Therefore, the tracking deviation is 1μ
It is very easy to correct within m.

In the present embodiment, the reproduction output of the tracking signal reproducing heads 18 and 32 was used as the tracking signal during reproduction of the video signal, but during reproduction, the reproduction of the video signal recording / reproducing head was performed. The tracking signal may be extracted from the signal by the BPF and used as the tracking control signal.

Further, in the present embodiment, the feedback control of the tracking signal is performed by the position control of the head base, but the control system by the rotation control of the capstan motor, the control system by the rotation control of the rotary cylinder, or the tape. It can also be applied to control systems by changing the support post position and changing the tape running path.

When a time reference for determining an absolute track recording position, which is related to the standard of the recording signal form, is required, for example, phase information of the control signal recorded on the tape edge adopted in the VHS system, etc. Is available.

[0033]

As described above, according to the present invention, since the linearity of the recording track can be dramatically improved, a VTR having a recording track width of 5 μm or less can be realized. Further, since the recording density of the magnetic tape can be made extremely high by narrowing the track, it is possible to increase the recording time, increase the recording capacity, downsize the VTR by downsizing the cassette half for the magnetic tape, and increase the time. Can make great progress.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts in an embodiment of the present invention.

FIG. 2 is a diagram showing a tape / head system according to an embodiment of the present invention.

FIG. 3 is a diagram showing tracking accuracy in one embodiment of the present invention.

[Explanation of symbols]

 1 signal recording section 2 tape / head section 3 video signal input terminal 4 recording side video signal processing circuit 5, 8 recording amplifier 6 tracking signal generating circuit 8 magnetic tape 9 tracking signal recording head array 10-16 tracking signal recording head 18, 32 Tracking signal playback head 19, 33 Video signal recording / playback head 20 Magnetic head scanning direction 21, 23 Playback amplifier 22 Playback side video signal processing circuit 24 Tracking signal playback time axis error detection circuit 25 Head relative height control circuit 26 Video signal output Terminal 27 Rotating cylinder 28, 29 Fixed post 30 Capstan motor 31 Pinch roller 34 Rotating direction of rotating cylinder 35, 38 Head base 36, 39 Piezoelectric element 37, 40 Direction in which relative height of head base changes 41 Tracking signal Scanning track of raw head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 5/7826

Claims (13)

[Claims] 1. A magnetic recording / reproducing apparatus for recording / reproducing information by obliquely scanning a magnetic head arranged on the circumference of a rotating cylinder on a magnetic tape wound on the rotating cylinder, wherein Means for forming a plurality of tracking signal tracks in a direction perpendicular to the width direction, a first magnetic head arranged on the circumference of the rotating cylinder for reproducing the tracking signal, and a circumference of the rotating cylinder. A second magnetic head arranged above and for recording or reproducing a signal inputted from the outside, a rotary cylinder motor for rotating the rotary cylinder, and a reproduction time interval of the reproduced tracking signal is a recording interval of the tracking signal. A magnetic recording / reproducing apparatus including a control circuit for controlling a relative positional relationship in which the magnetic head scans the tape so that the values are proportional to each other. Place 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the reproduced tracking signal is a tracking signal reproduced by the first magnetic head. 3. The magnetic recording / reproducing apparatus according to claim 1, wherein the reproduced tracking signal is a tracking signal reproduced by the second magnetic head. 4. A magnetic recording / reproducing device for recording / reproducing information by obliquely scanning a magnetic head arranged on the circumference of a rotating cylinder onto a magnetic tape wound on the rotating cylinder, the magnetic recording / reproducing apparatus comprising: When a plurality of tracking signal tracks are formed in a direction perpendicular to the width direction, a magnetic head arranged on the circumference of the rotary cylinder for recording or reproducing a signal input from the outside, and the rotary cylinder are provided. Control the relative positional relationship between the rotating cylinder motor and the magnetic head scanning the tape so that the reproduction time interval of the tracking signal reproduced by the magnetic head becomes a value proportional to the recording interval of the tracking signal. And a magnetic recording / reproducing apparatus including a control circuit. 5. The magnetic recording / reproducing apparatus according to claim 1, wherein the output of the control circuit is input to a drive device that changes the relative height of the first magnetic head with respect to the rotation surface of the rotating cylinder. 6. The magnetic recording / reproducing apparatus according to claim 1, wherein the output of the control circuit is input to a drive circuit for controlling the rotation of the rotary cylinder motor. 7. A magnetic recording / reproducing apparatus according to claim 1, wherein the output of the control circuit is input to a drive circuit for controlling the rotation of the tape running drive motor. 8. A magnetic recording / reproducing apparatus according to claim 1, wherein the output of the control circuit is inputted to a drive circuit for controlling a tape traveling path in the tape traveling mechanism system. 9. A device according to claim 1, wherein the means for forming a plurality of tracking signal tracks in a direction perpendicular to the width direction of the magnetic tape is a plurality of magnetic heads arranged in the tape width direction. Magnetic recording and reproducing device. 10. The magnetic recording / reproducing apparatus according to claim 9, wherein the magnetic head is a thin film head array. 11. The magnetic recording / reproducing apparatus according to claim 1, wherein the plurality of tracking signal tracks are formed after the magnetic tape passes through the full width erasing head. 12. A magnetic head for forming a plurality of tracking signal tracks when a magnetic head for recording or reproducing an externally input signal is in a recording mode, and a magnetic head for recording or reproducing an externally input signal is in a reproduction mode. 5. The magnetic recording / reproducing apparatus according to claim 1 or 4, wherein the plurality of tracking signal tracks are not formed when the magnetic recording medium is in the state of. 13. The magnetic recording / reproducing apparatus according to claim 1, wherein the plurality of tracking signals have the same interval.