JP2001006139A - Magnetic recording and reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize satisfactory automatic tracking during reproduction of a magnetic tape by recording an information signal at every other track on the magnetic tape being transported in a forward direction by means of either a first or second pair of rotary magnetic heads, and after recording in a backward direction, inverting the magnetic tape into the backward direction and recording the information signal at every other track. SOLUTION: During a recording operation for a magnetic tape T, an upper drum (rotary drum) to which first and second pairs of rotary magnetic heads are attached is driven to rotate at a predetermined rotation period T, and a magnetic tape T is wound around the upper drum over a predetermined angle in a helical manner. In this condition, the magnetic tape T is transported in forward and backward directions at a predetermined angle. During recording in the forward direction of the magnetic tape T, input information signals such as an analog image signal or the like are recorded at every other track on the magnetic tape T in the order of a track A1, a track B 1, a track A2, a track B2, a track A3,..., by means of the first pair of rotary heads. Thereafter, the magnetic tape T is inverted into the backward direction and transported.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tracking technique in a magnetic recording / reproducing apparatus such as a helical scan type VTR, in which an information signal is reciprocally recorded / reproduced by a rotary magnetic head by reciprocating a magnetic tape.

[0002]

2. Description of the Related Art Current helical scan type VTRs have only one running direction of the magnetic tape during recording. Therefore, when reproducing an information signal such as a recorded analog video signal or digital video signal, the magnetic tape must be rewound until the start of recording. Therefore, when recording is to be resumed after recording to the end of the magnetic tape, the magnetic tape must be rewound to the beginning,
When endless recording is to be performed as in a monitoring VTR, there has been a problem that a recording signal is lost for the rewind operation time.

[0003] In order to enable continuous recording of an information signal such as an analog video signal or a digital video signal in a VTR for a long time, an apparatus for recording and reproducing by reciprocating a magnetic tape has been proposed. There are mainly two methods for reciprocating the magnetic tape. As a first method, the recording area of the magnetic tape is divided into two steps in the width direction, and one area is used for recording in the forward direction (forward direction) and the other area is used for recording in the backward direction (reverse direction). Some are used.

However, as a method of dividing the recording area into two upper and lower stages on the magnetic tape, it is necessary to move the position of the recording / reproducing head up and down between the forward path and the backward path.
The configuration of the R mechanism must be changed significantly, which is not very practical.

On the other hand, a second method is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 0-85316, there is a recording method in which every other recording track is recorded on the outward path and recorded on an unrecorded track area formed between the recorded tracks on the return path.

FIGS. 11 (a) and 11 (b) are a top view and a side view of a main part of a rotating four-head type magnetic recording / reproducing apparatus to which a conventional reciprocating recording / reproducing method can be applied, and FIG. 4
FIG. 3 is a diagram for explaining an operation of reciprocating recording by a head type magnetic recording / reproducing apparatus.

As shown in FIGS. 11A and 11B, in a rotating four-head magnetic recording / reproducing apparatus 100 to which a conventional reciprocating recording / reproducing method can be applied, a magnetic tape T is guided by guide poles 101 and 102. And travels in the forward and backward directions while spirally contacting the outer peripheral surface of the guide drum 103 for approximately 180 °. The rotating disk 104 is rotatably held in the direction of the arrow between the upper and lower drums of the guide drum 103, and four video heads 105A to 105D are arranged at 90 ° divided positions on the outer peripheral edge of the rotating disk 104. 1800r by a head motor (not shown)
It is rotated at a predetermined speed of pm.

At this time, video heads 105A, 105A facing each other at 180 ° apart along the outer peripheral edge of the rotating disk 104.
105B has its azimuth angle + α ° with its gap inclined clockwise from the vertical direction by an angle α °.
On the other hand, the video heads 105C and 105D, which are 90 ° apart from each other and 180 ° apart from the video heads 105A and 105B, have their gaps inclined at an angle α ° counterclockwise from the vertical direction so that the azimuth angle −
Set to α °.

In FIG. 11, reference numeral 106 denotes an erasing head, and 107 denotes an audio control head.

Then, as shown in FIG. 12A, when the magnetic tape T is run and recorded in the forward direction (F direction), the video heads 105A and 105B use the track A for recording.
Recording is performed every other track in the order of 1, 1, B1, A2, and B2. At this time, an unrecorded area for one track is left between the recorded tracks so that a track for backward recording can be arranged.

On the other hand, the magnetic tape T is moved in the backward direction (R direction).
If the magnetic tape T is simply reversed when recording while traveling, the video heads 105C and 105D cross the recorded outward track, as shown in FIG. 12B.

Therefore, when recording the magnetic tape T while traveling in the backward direction (R direction), first, as shown in FIG. 12 (c), after detecting the reversal position, the capstan servo circuit (not shown) performs capping. The stun motor is stopped, and the inclination angle of the track scanning of the video heads 105C and 105D is corrected so as to match the inclination angle at the time of recording in the forward direction, and then the unrecorded track area formed between the recorded tracks is filled. Video heads 105C and 105D
Thus, recording is performed on every other track in the order of tracks C1, D1, C2, and D2. At the lower end of the magnetic tape T, a control pulse is supplied from the audio control head 107 by the audio control head 107 during the outward recording of the magnetic tape T.
Is recorded in synchronism with the rotation cycle of.

[0013]

By the way, in the rotating four-head type magnetic recording / reproducing apparatus 100 to which the above-mentioned conventional reciprocating recording / reproducing method can be applied, the video head 1 for forward recording is used.
05A and 105B are set to the same azimuth angle + α °, while video heads 105C and 10
5D are set to the same azimuth angle -α °,
When information signals such as analog video signals or digital video signals are recorded back and forth on the magnetic tape T by the video heads 105A to 105D, the video heads 105A to 105D
Tracks recorded by 5D have opposite azimuth angles ± α ° between adjacent tracks, so that crosstalk does not occur between adjacent tracks.

Here, when reproducing a track recorded on the magnetic tape T, the video heads 105A and 105A for forward recording are used.
Of the tracks 105B, the tracks recorded by the video head 105A can be reproduced not only by the video head 105A but also by the video head 105B having the same azimuth angle as the video head 105A. Of the tracks 105D, the tracks recorded by the video head 105C are
The video head 105C
The video head 105D having the same azimuth angle as described above can also reproduce.

However, the video heads 105A, 1
When a track recorded by the video head 105A for forward recording is reproduced by the video head 105B due to factors such as variations in the mounting height of the 05B to the rotating disk 104, the reproduction output is higher than that by the video head 105A. Accordingly, the reproduction image quality also deteriorates, and similarly, when a track recorded by the video head 105C for return path recording is reproduced by the video head 105D, the reproduction output is higher than that by the video head 105C. This causes a problem because the reproduced image quality is also deteriorated due to the deterioration.

Therefore, when reproducing a magnetic tape T on which an information signal such as an analog video signal or a digital video signal is reciprocally recorded, the track is automatically tracked by a video head used for recording, and the magnetic recording / reproducing can be performed satisfactorily. A device is desired.

[0017]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has been made in a state where a magnetic tape is spirally wound at a predetermined angle around a rotating drum to which a plurality of rotating magnetic head pairs are attached. A magnetic recording / reproducing apparatus that reciprocally records and reproduces information signals on the magnetic tape by the plurality of pairs of rotating magnetic heads while transferring the magnetic tape at a predetermined speed in a reciprocating direction; And a first pair of rotating magnetic heads having a predetermined azimuth angle and 180 degrees apart from each other along the outer circumferential surface of the rotating drum at a position different from the first pair of rotating magnetic heads.ら れ Mounted away and
The above-mentioned rotary drum, in which a second rotary magnetic head pair having an azimuth angle opposite to the azimuth angle of the first rotary magnetic head pair is mounted so as to intersect about the drum axis, is rotatable at a rotation period T. An information signal is recorded every other track on the magnetic tape being transported in the outward direction by the rotating drum assembly to be supported and one of the first and second rotating magnetic head pairs. Means for inverting the magnetic tape in the backward direction after forward recording, and recording information signals every other track in the area between tracks recorded by the one rotating magnetic head pair by the other rotating magnetic head pair; Means for recording a control pulse on the magnetic tape in synchronism with the rotation period T of the rotary drum when recording the magnetic tape in the forward path; If the rotation period of T is T, the tracking search range at the time of auto tracking is limited to T / 2 or less, and the track recorded by one of the first and second pairs of rotating magnetic heads is Means for performing auto-tracking within the tracking search range T / 2 by the one rotating magnetic head while referring to the control pulse, a recording locus in the forward direction by the one rotating magnetic head pair, and the other rotating magnetic head. Means for matching the recording trajectory of the head pair in the homeward direction.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a magnetic recording / reproducing apparatus according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is an overall configuration diagram for explaining a magnetic recording / reproducing apparatus according to the present invention.

As shown in FIG. 1, a magnetic recording / reproducing apparatus 1 according to the present invention employs a helical scan system using a rotating magnetic head, and a magnetic tape T is reciprocated and mounted on an upper drum (rotating drum) 14. First and second rotating magnetic head pairs (15A, 15B), (15C, 15D)
The rotary magnetic head assembly 10 reciprocally records and reproduces information signals such as analog video signals or digital video signals on the magnetic tape T, and transports the magnetic tape T at predetermined speeds in the forward and backward directions. The capstan 2 and the pinch roller 3 and the magnetic tape T are pulled out of a tape cassette (not shown), and the rotary magnetic head assembly 10
A pair of tape loading members 4 and 4 movably provided on the left and right sides of the rotary magnetic head assembly 10 so as to spirally wind over a predetermined angle (approximately 180 °), and a right side of the rotary magnetic head assembly 10. A control head 5 for recording and reproducing a control pulse CP (FIG. 8) at the lower end of the magnetic tape T; a system control circuit 6 for controlling the overall operation of the apparatus 1; A capstan servo circuit 7 for performing auto-tracking on tracks recorded on the magnetic tape T,
It comprises a drum servo circuit & tilt angle corrector 8 for controlling the drive and tilt angle of the rotary magnetic head assembly 10, and a signal processing block 9 for processing information signals for recording and reproduction.

The above-mentioned capstan servo circuit 7 controls the driving of the capstan 2 based on a control signal from the system control circuit 6, and sends a control signal to the capstan 2 to cause the capstan 2 and the pinch roller to move. 3, the magnetic tape T is transported in a reciprocating direction at a predetermined speed at the time of reciprocal recording / reproducing while holding the magnetic tape T therebetween. Further, the capstan servo circuit 7 performs the first and second rotating magnetic head pairs (15A, 15B) and (15C, 15D) during reciprocating reproduction of the magnetic tape T, as described later.
Of the tracks recorded by one of the rotating magnetic heads, the head reproducing output is generated by one rotating magnetic head within the tracking search range T / 2 (where T is the rotation cycle of the upper drum 14) while referring to the control pulse. Auto tracking is applied to maximize.

When recording on the magnetic tape T in the forward direction, the control head 5 is synchronized with the rotation period T of the upper drum 14 which forms a part of the rotary magnetic head assembly 10.
Control pulse CP on the lower end of the magnetic tape T
(FIG. 8) is recorded and the duty ratio of the control pulse is changed only when reversing from the forward direction to the backward direction or from the backward direction to the forward direction. The capstan servo circuit 7 is controlled by the control pulse reproduced by the control head 5 at the time of recording in the backward direction on the magnetic tape T, at the time of the second and subsequent forward and backward recordings, and at the time of reciprocal reproduction of the magnetic tape T. In addition to controlling the travel of the magnetic tape T through the same way as when recording in the outward direction, the control unit also monitors the duty ratio of the control pulse for a change.

The above-described drum servo circuit and angle correction unit 8
Is connected to a drum control motor or the like of the rotary magnetic head assembly 10 and controls the drum rotation at a predetermined rotation speed by a drum servo circuit 8A (FIG. 5), as described later. ), The inclination angle correction control of the rotary magnetic head assembly 10 is performed. By this tilt angle correction control, the first and second rotating magnetic head pairs (15
A, 15B) and (15C, 15D), the recording locus in the forward direction (forward direction) by the pair of rotating magnetic heads and the recording locus in the backward direction (reverse direction) by the other rotating magnetic head pair. Are matched.

The above-mentioned signal processing block 9 is connected to the first and second pairs of rotating magnetic heads (15A, 15B) and (15C, 15D) attached to the rotating magnetic head assembly 10, and performs signal processing for recording and reproduction. I do.

Next, the rotating magnetic head assembly 10 described above is used.
Will be described with reference to FIGS.

FIG. 2 is a longitudinal sectional view showing a rotary magnetic head assembly which is a main part of the present invention, FIG. 3 is an exploded perspective view showing the rotary magnetic head assembly, and FIGS. FIG. 5 is a top view for explaining the first and second pairs of rotating magnetic heads attached to the rotating magnetic head assembly, and a mounting position diagram. FIG. 5 is a configuration diagram schematically showing the entire configuration of the rotating magnetic head assembly.
FIGS. 6A and 6B are schematic diagrams for explaining the operation of the rotating magnetic head assembly.

The rotary magnetic head assembly 10 described above is an essential part of the present invention. The rotary magnetic head assembly 10 is used by the applicant for variable speed reproduction (high-speed search reproduction, slow reproduction, still reproduction). DD that allows the rotating magnetic head to follow the recording marks on the magnetic tape so that no band noise occurs on the screen even if the rotating magnetic head reproduces across the recording marks (signal tracks) recorded on the magnetic tape.
(Dynamic Drum) system is developed, and this DD system is applied to the reciprocating recording / reproducing operation of the magnetic tape T in the present embodiment, and the following first and second rotating magnetic head pairs ( 15A, 15
B) and (15C, 15D).

As shown in FIGS. 2 and 3, DD (Dyn
The configuration of a rotary magnetic head assembly 10 employing an amic drum system includes a drum base 11 fixedly mounted on a chassis base (not shown).
1, a lead ring 12, a lower drum 13, and an upper drum (rotary drum) 14 are assembled in this order from below to above.

First, on the outer circumference of the upper drum 14, a tape sliding contact surface 14a for winding and guiding the magnetic tape T over a predetermined angle (approximately 180 °) is formed in a cylindrical shape. A pair of first and second rotating magnetic heads (15A, 15B) and (15C, 15D) are mounted close to the lower drum 13 along the surface 14a.

Here, as shown in an enlarged manner in FIGS. 4A and 4B, the first rotating magnetic head pair (15A, 15B)
Are mounted 180 degrees apart from each other along the outer peripheral surface of the upper drum 14 so as to face each other.
For A and 15B, the gap is inclined clockwise from the vertical direction by an angle α °, and is set to a predetermined azimuth angle + α °. At this time, specifically, each rotating magnetic head 15
The predetermined azimuth angle + α ° of A and 15B is, for example, +6
° is set.

Further, the second rotating magnetic head pair (15C,
15D) are attached 180 degrees apart from each other along the outer peripheral surface of the upper drum 14 and 90 degrees apart from the first rotating magnetic head pair (15A, 15B). , Each rotating magnetic head 15
C and 15D have their gaps inclined counterclockwise by an angle α ° from the vertical direction, and are set to a predetermined azimuth angle −α °. At this time, specifically, the predetermined azimuth angle −α ° of each of the rotating magnetic heads 15C and 15D is set to −6 °, for example.

Here, the first rotating magnetic head pair (15
A, 15B) and the second rotating magnetic head pair (15C, 15C).
D) is mounted on the upper drum 14 so as to intersect with the drum shaft 16 as a center, and the second rotating magnetic head pair (15A, 15B) has a second azimuth angle α ° with respect to a predetermined azimuth angle α °. The predetermined azimuth angle -α ° of the pair of rotating magnetic heads (15C, 15D) is reverse azimuth.

In this embodiment, the first rotating magnetic head pair (15A, 15B) and the second rotating magnetic head pair (15
C, 15D) means 90 along the outer peripheral surface on the upper drum 14.
も の Although they are mounted apart from each other, they are not limited to this, and they may be mounted at different positions. If the traveling of the magnetic tape T is controlled so that the backward recording track can be recorded between the forward recording tracks during the backward recording. Good thing.

Further, the first and second rotating magnetic head pairs (1
The head track widths of 5A, 15B) and (15C, 15D) are set to W, and the track locus on the magnetic tape T is formed by the head track width W.

Next, the lower drum 13 has a drum shaft 16 pressed into the center thereof.
4 is coaxially supported via upper and lower bearings 17,17. A magnetic tape T is provided around the lower drum 13.
The tape sliding surface 13a for winding and guiding the
Is formed in a cylindrical shape with substantially the same diameter as the tape sliding contact surface 14a. In the lower drum 13, a small-diameter portion 13b having a smaller diameter than the tape sliding contact surface 13a is formed spirally below the tape sliding contact surface 13a, and has a smaller diameter than the small-diameter portion 13b below the center of the bottom surface portion 13c. A lower small diameter portion 13d is formed so as to protrude toward a drum base 11 described later.

Only the upper drum 14, on which the first and second rotating magnetic head pairs (15A, 15B) and (15C, 15D) are integrally mounted, has a drum motor 18 (FIG. (Shown) by a predetermined rotation period T in the direction of the arrow. At this time, the drum motor 18 is configured by combining a stator 18 a fixed to the upper end side of the drum shaft 16 and a rotor 18 b that rotates integrally with the upper drum 14. Further, between the rotary transformer 19 attached to the upper drum 14 and the rotary transformer 20 attached to the lower drum 13, the first and second rotary magnetic head pairs (15A, 15B), (1
5C, 15D).

Further, a lead ring 12 having a spiral lead 12a for guiding a reference edge Te (shown only in FIG. 2) at the lower end of the magnetic tape T is provided below the outer periphery of the lower drum 13 with respect to the lower drum 13. It is provided separately. The lead ring 12 is loosely fitted in a state of being close to the outer peripheral surface of a spirally formed small diameter portion 13b below the lower drum 13, as shown in an enlarged view in FIG. Of the lead 12a is formed roughly from an annular portion 12b formed spirally at a predetermined angle and a bottom surface portion 12c. A central hole 12d is formed in the center of the bottom surface 12c of the lead ring 12 so as to penetrate therethrough.
A knife edge portion 12e to be fitted coaxially with the lower small diameter portion 13d of the lower drum 13 is formed in the inner peripheral portion of 2d. Therefore, the upper and lower drums 14, 13 coaxially supported by the drum shaft 16 can be coaxially fitted on the bottom surface 12c of the lead ring 12. On the upper surface of the bottom surface portion 12c of the lead ring 12, the first rotation fulcrums 12f on the left and the second rotation fulcrums 12g on the right as shown in FIG. 1
2g are protruded in the front and rear in the depth direction, respectively.
These left first fulcrum 12f, 12f and right second fulcrum 12f.
The rotating fulcrums 12g, 12g are lower drum 1 as described later.
3 is in contact with the back surface of the bottom portion 13c so as to be able to freely contact and separate. Further, on the bottom surface portion 12c of the lead ring 12, first left pivot points 11c, 11c and right second pivot points 11c formed on the upper surface 11a of the drum base 11 described below.
Four through-holes 12h are formed for entry of d and 11d. Also, the bottom surface portion 12c of the lead ring 12
Are provided with escape holes 12i, 1 into which first geared screws 21, 22 described later enter symmetrically about the drum shaft 16.
2i and screw holes 12j, 12j into which second geared screws 23, 24 to be described later are screwed.

Next, a drum base 11 serving as a base of the rotary magnetic head assembly 10 is fixedly installed below a lead ring 12. The drum base 11 is provided with a lower drum 13 at the center of the upper surface 11a, as shown in FIG.
A central escape hole 11b into which the lower small diameter portion 13d enters is formed, and the first rotation fulcrums 11c on the left and the second rotation fulcrums 11d on the right are symmetrically symmetrical about the drum shaft 16. 11d protrude forward and backward in the depth direction, respectively. These left first fulcrum 11c, 11
c and the right second rotation fulcrum 11d, 11d penetrate through four through holes 12h of the lead ring 12 and contact with the back surface of the bottom portion 13c of the lower drum 13 in a manner to be described later. In contact. Further, screw holes 11e, 11e into which first geared screws 21, 22 described later are screwed into the drum base 11 symmetrically about the drum shaft 16, and second geared screws 23, 24 described later enter. Through holes 11f are formed respectively.

As shown in FIG. 5, a compression spring 2 is provided between the drum base 11 and the lead ring 12 and between the drum base 11 and the lower drum 13, respectively.
5, 26 and 27 are mounted so that the above-mentioned parts are connected to each other in a predetermined state. The compression springs 25, 26, and 27 shown in the figure are functionally shown, and are provided at predetermined mounting portions.

The drum servo circuit 8A of the drum servo circuit & tilt angle correction unit 8 of the rotary magnetic head assembly 10 controls the upper drum 14 at a constant rotation speed in accordance with a command from the system control circuit 6. ing.

On the other hand, the inclination angle correction section 8B is controlled by a command from the system control circuit 6, and includes a DD motor (inclination angle driving motor) 8B1 as a power source and this D motor 8B1.
A speed reduction mechanism 8B2, 8B3 composed of a plurality of gears connected to the left and right with the D motor 8B1;
A rotary encoder 8B4 for detecting rotation of B1 and a preset sensor 8 for detecting a reference position of the speed reduction mechanism 8B2
B5.

At this time, the left reduction mechanism 8B2 is engaged with the first and second geared screws 21 and 23, and the right reduction mechanism 8B3 is engaged with the right first and second geared screws 22 and 2.
4 is engaged.

Further, a preset sensor 8B for position detection
As 5, for example, a configuration in which an arc-shaped light shielding plate is moved in an optical path in which a light emitting element and a light receiving element are arranged to face each other may be used. The preset sensor 8B5 outputs a signal output from the preset sensor 8B5 at the moment when the arc-shaped light shielding plate is removed from the optical path where the light emitting element and the light receiving element are arranged to face each other. It is used as information indicating the reference position of the drum shaft 16 of the three-dimensional object 10 and the reference position of the lead ring 12.

The amount of rotation of the light shielding plate from the reference position in the preset sensor 8B5 is
By knowing from the measurement of the number of output pulses from B4, the direction and amount of deviation of the rotary magnetic head assembly 10 from the reference position of the drum shaft 16 and the direction and amount of deviation of the lead ring 12 from the reference position are determined. You can ask.

The above-described tilt angle correction unit 8B moves the drum shaft 16 of the rotary magnetic head assembly 10 including the upper drum 14, the lower drum 13, and the lead ring 12 in the direction of arrow R or the direction of arrow L in FIG. The first and second geared screws 21 and 23 are tilted by predetermined amounts, respectively.
And a control operation for moving the right and second geared screws 22 and 24 forward and backward.

The lead ring 12 is also tilted by a predetermined amount in a predetermined direction under the control of the tilt angle correction unit 8B.
Thus, regardless of whether the traveling direction of the magnetic tape T is the forward direction or the backward direction, the magnetic tape T is determined by the rotation locus of the first and second rotating magnetic head pairs (15A, 15B) and (15C, 15D). The recording trace (signal track) drawn on T has a predetermined track angle, that is, a state in which the inclination angle has been corrected, and the lead 12a of the lead ring 12 moves along the movement locus of the reference edge Te of the magnetic tape T. Are matched.

As described above, by the operation of the tilt angle correction section 8B, the rotation trajectories of the first and second rotating magnetic head pairs (15A, 15B) and (15C, 15D) rotating in a predetermined direction are: The reciprocating recording / reproducing operation can be performed by setting the angle (track angle) between the magnetic tape T and the reference edge Te at a predetermined angle.

Next, the operation of the rotary magnetic head assembly 10 having the above configuration will be described in more detail with reference to FIGS. 6 (a) and 6 (b). The tilt angle correction unit 8B is used for variable speed reproduction during normal forward recording / reproduction.
Here, a description will be given by applying the inclination angle correction unit 8B at the time of reciprocal recording and reproduction.

First, as schematically shown in FIG.
When recording / reproducing the magnetic tape T in the forward direction, the drum shaft 16 is held in a neutral state, and the upper and lower drums 14 and 13 coaxially supported by the drum shaft 16 and the lead ring 12 are connected to the drum base. It is held substantially parallel to the drum base 11 without tilting with respect to the drum base 11. That is, the left and right first and second pivot points 1 on the drum base 11
1c, 11d and the left and right first and second pivot points 12f, 12g on the lead ring 12
3c is in contact with the back surface. At this time, the drum base 11
The left and right first geared screws 21 and 22 screwed into the lower drum 13 are retracted downward without contacting the bottom surface 13 c of the lower drum 13, while the left and right second geared screws 23 and screwed into the lead ring 12. 24 also retreats downward without contacting the bottom surface 13c of the lower drum 13. Also, the lower drum 13
Is urged toward the drum base 11 by a strong urging force of a compression spring 27 (FIG. 5) narrowly mounted between the drum base 11 and the lower drum 13, and the lead ring 12 is connected to the drum base 11 and the lead ring. The lower drum 13 is pressed by a weak urging force of compression springs 25 and 26 (FIG.
Side, the lower drum 13 is securely supported on the above-mentioned four pivot points while maintaining the height dimension, and the lead ring 12 is also securely maintained with the height dimension maintained. It is supported by. Therefore, the drum shaft 16 and the virtual drum shaft of the lead ring 12 match with high accuracy, and these shafts are perpendicular to the drum base 11. In this state, when reproducing the magnetic tape T recorded on the outward path, when the magnetic tape T runs at a predetermined speed while being guided along the reference edge Te by the lead 12a of the lead ring 12, the first and second rotations are performed. Magnetic head pair (15A, 15
The rotation trajectories B) and (15C, 15D) coincide with recording marks (signal tracks) recorded on the magnetic tape T.

Next, as schematically shown in FIG.
When performing the backward path recording on the magnetic tape T on which the forward path recording is performed, the drum shaft 16 is tilted in the direction of the arrow L so that the rotational path of the rotational magnetic head of the backward path recording may follow the rotational path of the rotational magnetic head recorded on the forward path. If you want to record
The DD motor 8B1 (FIG. 5) is driven in the opposite direction to rotate the right first and second geared screws 22 and 24 in a direction of pushing them upward, and to the left first and second geared screws 21. ,
23 is rotated in a direction to retract from the lower drum.

That is, when the right first geared screw 22 screwed to the drum base 11 is pushed upward, its upper end pushes up the right bottom surface portion 13c of the lower drum 13, so that Left first pivot 11
c contacts the left bottom surface portion 13 c of the lower drum 13, while the right second rotation fulcrum 11 on the drum base 11.
d is separated from the right bottom surface portion 13c of the lower drum 13. As a result, the upper and lower drums 14, 13 coaxially supported on the drum shaft 16 together with the lead ring 12, the first rotation fulcrum 11c on the drum base 11 against the urging force of the compression spring 27 (FIG. 5). Rotate counterclockwise around
The whole drum correction is performed.

Further, at the same time when the first geared screw 22 is pushed out, the right second geared screw 24 screwed to the lead ring 12 is also pushed upward in FIG. Abuts on the right bottom surface portion 13c, the reaction force causes the left first rotation fulcrum 12f on the lead ring 12 to move from the lower drum 13 to the left bottom surface portion 13c.
c on the other hand, the right second rotation fulcrum 12 g on the lead ring 12 is connected to the right bottom portion 13 of the lower drum 13.
Separate from c. As a result, the lead ring 12 rotates about the left first rotation fulcrum 12f in the direction of pushing down (clockwise) against the lower drum 13 against the urging force of the compression spring 26 to perform the primary correction. Is performed.

Then, the first screwed to the drum base 11
The secondary correction of the lead ring 12 with respect to the drum base 11 is performed by subtracting the primary correction by the second gear screw 24 screwed to the lead ring 12 from the entire drum correction by the gear screw 22. Thereby, the backward recording track can be recorded along the inclination of the outward recording track recorded on the magnetic tape T.

Although the embodiment has been described with reference to the embodiment shown in FIG. 6A for the forward path recording and the embodiment shown in FIG. 6B for the backward path recording, the present invention is not limited to this. When the embodiment shown in FIG. 6B is used, the drum shaft 16 may be inclined in the direction of arrow R in FIG.

Next, the signal processing circuit 9 described above,
The second rotating magnetic head pair (15A, 15B), (15
C, 15D) will be described with reference to FIG.

FIG. 7 is a diagram showing a configuration for exchanging information signals between the signal processing circuit and the first and second pairs of rotating magnetic heads.

In FIG. 7, reference numeral 38 denotes an input terminal of an information signal such as an analog video signal or a digital video signal to be recorded in the magnetic recording / reproducing apparatus 1 according to the present invention, and 39 denotes an input terminal of the present invention. Output terminal for an information signal such as an analog video signal or a digital video signal reproduced from the magnetic tape T by the magnetic recording / reproducing apparatus.

When the information signal supplied to the input terminal 38 is, for example, a video signal, the signal processing circuit 40 of the recording system converts the signal in the form of a frequency-modulated wave by a luminance signal into a low-frequency conversion carrier. A recording signal in the form of a frequency multiplexed signal with a color signal is provided to the amplifiers 41 and 42. An output signal from the recording amplifier 41 is supplied to a recording-side fixed contact R of a recording / reproducing switch 45, and an output signal from the recording amplifier 42 is supplied to a recording-side fixed contact R of a recording / reproducing switch 46. Is done.
The reproduction signal from the magnetic tape T is amplified by the preamplifiers 43 and 44 from the reproduction-side fixed contact points P in the recording and reproduction changeover switches 45 and 46, respectively, and is subjected to predetermined signal processing in the reproduction-system signal processing circuit 50. Output terminal 39
Is output from

When the magnetic recording / reproducing device is set to the recording operation mode, the recording / reproducing changeover switches 45 and 46 allow the movable contact v to be fixed to the recording side by a switching control signal given from the system control circuit 6. When the magnetic recording / reproducing apparatus is set to the reproducing operation mode, the movable contact v is switched to the reproducing-side fixed contact P by a switching control signal given from the system control circuit 6. Is switched to

The movable contacts v of the recording / reproducing changeover switches 45, 46 are connected to the movable contacts v of the rotary magnetic head selection switches 47, 48. The fixed contact A of the rotary magnetic head selection switch 47 is connected to a rotary magnetic head 15A having an azimuth angle + α ° provided on the upper drum 14 via a rotary transformer (not shown). The fixed contact C of the rotary magnetic head selection switch 47 is connected to the rotary magnetic head 1 having an azimuth angle -α ° provided on the upper drum 14.
5C is connected via a rotary transformer (not shown). On the other hand, the fixed contact B of the rotary magnetic head selection switch 48 is connected to the rotary magnetic head 15B provided on the upper drum 14 and having the azimuth angle + α °.
Are connected via a rotary transformer (not shown). The rotary magnetic head selection switch 4
The fixed contact D at 8 is connected to a rotary magnetic head 15D having an azimuth angle -α ° provided on the upper drum 14 via a rotary transformer (not shown).

The rotary magnetic head selection switch 47,
The movable contact 48 is switched to the fixed contacts A and B (or fixed contacts C and D) at the time of forward recording / reproduction by a switching control signal given from the system control circuit 6, and the fixed contacts C and D at the time of return recording / reproduction. D side (or fixed contacts A, B
Side).

Next, the recording / reproducing operation of the magnetic recording / reproducing apparatus 1 according to the present invention having the above configuration will be described with reference to FIGS. 1, 5, 7 and 8 to 9.

FIG. 8 is a diagram showing a recording track pattern reciprocally recorded by the magnetic recording / reproducing apparatus according to the present invention. FIG. 9 is a diagram showing a case where the track on the magnetic tape is automatically tracked in the magnetic recording / reproducing apparatus according to the present invention. FIG. 10 is a diagram showing a tracking search range, and FIG. 10 is a diagram showing a reproduction output for explaining an auto tracking operation on a magnetic tape in the magnetic recording / reproducing apparatus according to the present invention.

First, the first and second rotating magnetic head pairs (15A, 15B), (15C, 15D) are placed on the magnetic tape T.
The operation of reciprocally recording an information signal such as an analog video signal will be described.

When recording the magnetic tape T, the first and second rotating magnetic head pairs (15A, 15B), (15C, 15
D) is mounted on the upper drum (rotary drum) 14 at a predetermined rotation period T, and the magnetic tape T is wound around the upper drum 14 in a spiral manner over a predetermined angle (approximately 180 °). The magnetic tape T is transported at a predetermined speed in the reciprocating direction.

Here, at the time of outward recording on the magnetic tape T,
As shown in FIG. 7, the recording / reproducing changeover switches 45 and 46 are switched to the recording side, and the rotary magnetic head selection switch 4
7 and 48 have the azimuth angle + α ° connected to the fixed contact B and the rotary magnetic head 15A connected to the fixed contact A and having the azimuth angle + α ° connected to the fixed contact A by the switching control signal from the system control circuit 6. Switching to the rotary magnetic head 15B side.

Then, as shown in FIG.
At the time of outward recording, the first rotating magnetic head pair (15A,
15B), an information signal such as an analog video signal, etc.
1, A2, B2, A3,... Are recorded every other track. At this time, the control pulse CP is applied to the lower end of the magnetic tape T by the control head 5 so that the upper drum 14
The recording is performed in synchronization with the rotation period T, and the duty ratio of the control pulse CP is changed near the end point of the outward recording.

Thereafter, when the magnetic tape T is reversed in the backward direction (reverse direction) and recorded in the backward direction, the forward recording is stopped, the magnetic tape T is immediately reversed, and the magnetic tape T is transported in the backward direction. And the capstan 2 and the capstan servo circuit 7 start control of the magnetic tape T in the backward direction. At this time, control of the magnetic tape T in the backward direction is performed by reproducing the control pulse CP recorded in the forward path, and the backward track is positioned between the forward tracks. Almost simultaneously with the above,
By operating the tilt angle correction unit 8B, the recording trajectory in the forward direction (forward direction) by the first pair of rotary magnetic heads (15A, 15B) and the return path (reverse direction) by the second pair of rotary magnetic heads (15C, 15D) The inclination angle of the rotating drum assembly 10 is corrected so that the recording trajectory of the rotating direction coincides with the recording trajectory of the rotating direction.

On the other hand, at the time of homeward recording on the magnetic tape T, as shown in FIG.
8 by a switching control signal from the system control circuit 6
Switching between the rotating magnetic head 15C having an azimuth angle -α ° connected to the fixed contact C and the rotating magnetic head 15D having an azimuth angle -α ° connected to the fixed contact D is performed as shown in FIG. As shown, while controlling the tape running phase with reference to the recorded control pulse CP,
An information signal input by the second pair of rotating magnetic heads (15C, 15D) is magnetically recorded in an unrecorded track area formed between the recorded tracks recorded by the first pair of rotating magnetic heads (15A, 15B). On the tape T, the tracks C1,
.. Are recorded every other track in the order of D1, C2, D2,. At this time, the first rotating magnetic head pair (15A, 15A) is used.
The unrecorded track area formed between the recorded tracks recorded in B) is formed only at the time of the first outward recording in a state where the magnetic tape T is not used. It is recorded.

Similarly, by repeating the magnetic tape T a plurality of times in the reciprocating direction, continuous overwriting can be performed.

The state shown in FIG. 8 is described using the first pair of rotating magnetic heads (15A, 15B) during forward recording, and using the second pair of rotating magnetic heads (15C, 15D) during backward recording. However, conversely, using the second pair of rotating magnetic heads (15C, 15D) during forward recording and using the first pair of rotating magnetic heads (15A, 15B) during backward recording does not cause any problem. .

Here, after the reciprocating recording on the magnetic tape T, the adjacent tracks have opposite azimuth angles, so that good recording and reproduction can be performed with almost no crosstalk interference from the adjacent tracks. . In the reciprocating reproduction of the magnetic tape T, substantially the same operation as in recording is performed by switching the recording / reproduction changeover switches 45 and 46 to the reproduction side.

Next, the reproduction operation of the recorded track on the magnetic tape T will be described.

As shown in FIG. 9, when the forward recording track recorded by the first rotating magnetic head pair (15A, 15B) having the azimuth angle + α ° is reproduced, the rising edge of the control pulse corresponds to the azimuth angle + α °. Indicate the tracking positions of the tracks A1, A2,... Recorded by the rotating magnetic head 15A, and the falling edge of the control pulse has the azimuth angle + α °.
.. B indicate the tracking positions of tracks B1,.

The tracks C2, D2, C
3,... Indicate backward recording tracks recorded by the second pair of rotating magnetic heads (15C, 15D) having the azimuth angle -α °.

The period from the predetermined rising edge of the control pulse to the next rising edge (or from the predetermined falling edge to the next falling edge) is a period corresponding to the rotation period T of the upper drum 14.

Here, in order to perform auto-tracking so that the track A1 recorded by the rotating magnetic head 15A having the azimuth angle + α ° is reproduced by the rotating magnetic head 15A, assuming that the rotation period of the upper drum 14 is T, The magnetic tape T is automatically tracked with respect to the rotary magnetic head 15A by the capstan 2 and the capstan servo circuit 7 so that the tracking range is limited to within T / 2 around the rising edge of the control pulse corresponding to the track A1. I have. In other words, when the magnetic tape T is swung left and right within ± T / 4 around the rising edge of the control pulse with respect to the rotating magnetic head 15A, the reproduced output of the rotating magnetic head 15A peaks at the track A1 by the hill-climbing method. Since the waveform becomes a shape, the rotating magnetic head 15A is in a just-on-track state on the track A1 at a position where the reproduction output of the rotating magnetic head 15A is maximum. At this time, since the tracking range is limited to within T / 2, the rotating magnetic head 15A cannot reproduce the track B1 recorded by the rotating magnetic head 15B.

Therefore, the track A1 recorded by the rotary magnetic head 15A is subjected to auto-tracking within the tracking range T / 2 by the rotary magnetic head 15A while referring to the rising edge of the control pulse.
When the rotary magnetic head 15A is just on track on the track A1, as shown in FIG.
From the rotary magnetic head 15A is best,
Along with this, the output from the track B1 by the rotating magnetic head 15B paired with the rotating magnetic head 15A necessarily becomes the best, and thereafter, the reproduction output of the rotating magnetic head 15A is automatically adjusted while maintaining the best state. What is necessary is just to turn off tracking.

If the track A1 recorded by the rotating magnetic head 15A is not automatically tracked by the rotating magnetic head 15A, the reproduced output of the rotating magnetic head 15A from the track A1 is small as shown in FIG. Thus, the reproduction output from the track B1 by the rotating magnetic head 15B paired with the rotating magnetic head 15A is necessarily reduced.

Further, the rotating magnetic head 15A having a different azimuth angle from the track A1 recorded by the rotating magnetic head 15A is different from the rotating magnetic head 15A at the time of recording.
If auto-tracking is performed by B, FIG.
Although the reproduction output of the rotary magnetic head 15B from the track A1 can be improved as in
Track B by rotating magnetic head 15A paired with B
The playback output from 1 becomes small. The reason for this is
It is difficult to attach the two rotating magnetic heads 15A and 15B to the upper drum 14 according to the design values. For example, when the track width becomes narrower in high-density recording and there is an error in the height direction, the result shown in the drawing is remarkable. appear.

As described above, the rotary magnetic head 15B
The same result as described above can also be obtained by applying auto-tracking to the track B1 recorded in step 2 so as to maximize the head reproduction output within the tracking range T / 2 by referring to the falling edge of the control pulse. Is obtained.

Furthermore, when auto-tracking is performed during the backward reproduction, the rising edge or the falling edge of the control pulse is detected, and the control pulse is delayed by a predetermined time so as to correspond to the backward recording track to be subjected to auto-tracking. By doing so, it is possible to perform auto-tracking even on the backward recording track for which auto-tracking is desired, so that the head reproduction output is maximized within the tracking range T / 2 as described above.

[0083]

According to the magnetic recording and reproducing apparatus of the present invention described in detail above, an information signal such as an analog video signal is reciprocally recorded on a magnetic tape by the first and second rotating magnetic head pairs and reproduced. In particular, if the rotation period of the rotating drum is set to T during reproduction to the magnetic tape, the tracking search range at the time of auto-tracking is limited to within T / 2, and the first and second rotating magnetic head pairs are Auto-tracking is performed by one rotating magnetic head so as to maximize the head reproduction output within the tracking search range T / 2 while referring to the control pulse for the track recorded by one rotating magnetic head. A rotating magnetic head that records a track on a magnetic tape and a rotating magnetic head that reproduces this track can be set identically, in other words. Since one of the rotary magnetic head on a track recorded at one of the rotary magnetic head can be just on-track can be obtained a good reproduction video output.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram for explaining a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view showing a rotary magnetic head assembly which is a main part of the present invention.

FIG. 3 is an exploded perspective view showing the rotating magnetic head assembly.

FIGS. 4A and 4B are a top view and a mounting position diagram for explaining first and second rotating magnetic head pairs mounted on the rotating magnetic head assembly.

FIG. 5 is a configuration diagram schematically showing the entire configuration of the rotating magnetic head assembly.

FIGS. 6A and 6B are schematic views for explaining the operation of the rotary magnetic head assembly.

FIG. 7 is a diagram showing a configuration for transmitting and receiving information signals between a signal processing circuit and first and second pairs of rotating magnetic heads.

FIG. 8 is a diagram showing a recording track pattern recorded reciprocally by the magnetic recording / reproducing apparatus according to the present invention.

FIG. 9 is a diagram showing a tracking search range when a track on a magnetic tape is automatically tracked in the magnetic recording / reproducing apparatus according to the present invention.

FIG. 10 is a diagram showing a reproduction output for explaining an auto tracking operation on a magnetic tape in the magnetic recording / reproducing apparatus according to the present invention.

FIGS. 11A and 11B are a top view and a side view of a main part of a rotating four-head magnetic recording / reproducing apparatus to which a conventional reciprocating recording / reproducing method can be applied.

FIG. 12 is a diagram for explaining an operation of reciprocating recording by the rotating four-head type magnetic recording / reproducing apparatus shown in FIG. 11;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording / reproducing apparatus, 2 ... Capstan, 3 ... Pinch roller, 5 ... Control head, 6 ... System control circuit, 7 ... Capstan servo circuit, 8 ... Drum servo circuit & inclination angle correction part, 8
A: drum servo circuit, 8B: tilt angle correction unit, 9: signal processing block, 10: rotating magnetic head assembly, 11:
Drum base, 12: Lead ring, 13: Lower drum,
14: rotating drum (upper drum), 15A, 15B: first
Rotating magnetic head pair, 15C, 15D: second rotating magnetic head pair, 16: drum shaft, + α °: azimuth angle of first rotating magnetic heads 15A, 15B, −α °: second rotating magnetic head 15C , 15D azimuth angle, T ... magnetic tape.

Claims (1)

[Claims] The magnetic tape is transported at a predetermined speed in a reciprocating direction in a state where the magnetic tape is spirally wound at a predetermined angle around a rotary drum to which a plurality of rotary magnetic head pairs are attached. A magnetic recording / reproducing apparatus for reciprocally recording and reproducing an information signal on and from the magnetic tape by using a pair of rotating magnetic heads, wherein the magnetic head is mounted 180 degrees apart along the outer peripheral surface of the rotating drum and has a predetermined azimuth angle. A first rotating magnetic head pair, which are mounted at a position different from the first rotating magnetic head pair at a distance of 180 ° along the outer peripheral surface of the rotating drum, and wherein the azimuth angle of the first rotating magnetic head pair is And a second rotating magnetic head pair having an opposite azimuth angle with respect to the rotating drum. A recording drum assembly, and an information signal is recorded at every other track on the magnetic tape being transferred in the forward direction by one of the first and second rotating magnetic head pairs. Means for inverting the magnetic tape in the backward direction after recording, and recording an information signal every other track in an area between tracks recorded by the one rotating magnetic head pair by the other rotating magnetic head pair; Means for recording a control pulse on the magnetic tape in synchronization with the rotation period T of the rotating drum during the outward recording of the tape, and tracking at the time of auto-tracking, where T is the rotation period of the rotating drum when reproducing the magnetic tape. The search range is limited to T / 2 or less, and the track recorded by one of the first and second rotating magnetic head pairs is Means for performing auto-tracking within the tracking search range T / 2 by the one rotating magnetic head while referring to the control pulse, a recording locus in the forward direction by the one rotating magnetic head pair, and the other rotating magnetic head. Means for matching the recording trajectory of the head pair in the backward direction.