JPH0442421A - Tracking controller for video tape recorder - Google Patents

Abstract

PURPOSE:To perform noiseless reproduction faster than ever by also performing the speed correction of a drum motor on which a magnetic head is loaded in the same polarity direction as that of a capstan motor when a magnetic tape is fed at speed of (n) times the speed in ordinary reproduction. CONSTITUTION:When a command signal (d) for reproduction at speed of (n) (n: real number) times is issued from a reproduction speed command part 13, a capstan motor control means 14 feeds the magnetic tape 2 at speed of (n) times the ordinary reproducing speed. Furthermore, the command signal (d) from the reproduction speed command part 13 is inputted to a drum speed command means 16, and issues a command signal (e) at speed of (1+alpha.n) (alpha: <=1 positive real number) times the ordinary reproducing speed as the speed command of the drum motor 7, and a drum control means 17 compares the command signal (e) with the output signal of a speed sensor 18 which detects the rotating speed of the drum motor 7, and rotates a drum 8 at speed of (1+alpha.n) times the ordinary reproducing speed. Thereby, it is possible to perform the noiseless reproduction at tape speed faster than ever with the head actuator of the same movable dynamic range.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tracking/king control device for a video tape recorder (hereinafter referred to as VTR) that performs noiseless variable speed playback.

2. Description of the Related Art Conventionally, in VTR tracking control devices capable of noiseless variable speed playback, the rotational speed of the drum motor is kept constant at the same level as the normal playback speed, and the magnetic head is rotated. Tracking control was performed by moving the magnetic head using a small actuator to follow the recording track.

Problems to be Solved by the Invention However, in the conventional configuration, there is a limit to the dynamic range of the actuator that moves the magnetic head, so there is a limit to the speed at which the tape can be reproduced without noise.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tracking control device for a VTR that is capable of noiseless reproduction at a tape speed higher than that of a conventional head actuator with the same movable dynamic range as the conventional one.

Means for Solving the Problems In order to solve the above problems, the tracking control device for a VTR of the present invention includes a drum motor which is equipped with a magnetic head and rotates integrally with the drum motor, and a cap for running the magnetic tape at a substantially constant speed. In a video tape recorder that has a stun motor and performs helical scanning recording and playback on the magnetic tape, when the playback speed is varied by n times the normal playback speed (n is a real number), the rotational speed of the capstan motor is capstan control means for controlling the rotational speed of the drum motor to be n times the normal playback speed; and controlling the rotational speed of the drum motor to be (l+α·n) times the normal playback speed (α is a positive real number of 1 or less). a head actuator that moves the magnetic head substantially perpendicularly to a recording track formed on the magnetic tape; and a head actuator that determines the relative position of the recording track and the magnetic head from a reproduction output signal of the magnetic head. Tracking error detection means for detecting a tracking error, and track control means for controlling the head actuator to eliminate relative positional deviation between the recording track and the magnetic head according to the output of the tracking error detection means. It is.

Effect of the present invention With the above-described configuration, when the magnetic tape runs at n times the speed during normal playback, the speed of the drum motor on which the magnetic head is mounted is also corrected in the same polar direction as the capstan motor (normal playback speed). Therefore, the deviation between the relative velocity vector of the magnetic head and the magnetic tape and the recording track locus is reduced compared to the case where the speed of the drum motor is not corrected. If the dynamic range of movement of the head actuator for making the magnetic head follow the recording track is constant, the deviation between the relative velocity vector of the magnetic head and the magnetic tape and the recording track trajectory will be alleviated compared to the case where the speed of the drum motor is not corrected. The speed of the magnetic tape can be increased by the same amount as the amount of noise, making it possible to play back noiselessly at higher speeds than with conventional devices.

Embodiment Hereinafter, a VTR control device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows V T I? in one embodiment of the present invention. 1 shows a configuration diagram of a tracking control device of FIG.

The magnetic tape 2 wound on the supply reel 1 is transported by a capstan shaft 4 and a pinch roller 5, which rotate together with a capstan motor 3, and is taken up on a take-up reel 6. Furthermore, the magnetic tape 2 includes a post P1 and a post P2.
It is wound at an appropriate angle around the drum 8 which rotates together with the drum motor 7. A magnetic head 9 mounted on the drum 8 helically scans the magnetic tape 2.

Here, it is assumed that signals are recorded in advance on the magnetic chip 12 at a predetermined tape speed and head speed, and a recording track is formed.

The head actuator 10 is installed on the drum 8 and moves the magnetic head 9 substantially perpendicularly to the recording track on the magnetic tape 2. When reproducing a recorded signal, a reproduced signal a obtained from the recording head 9 is input to a tracking error detection means 11. The tracking error detection means 11 detects the envelope of the input reproduction signal a, and compares it with the magnitude of the reproduction signal envelope when the ift head 9 is following the recording track (on-track state). , outputs a signal proportional to the displacement of the magnetic head 9 with respect to the recording track.

The tracking control means 12 generates a voltage signal C proportional to the signal S and supplies it to the head actuator 10. The head actuator 10 is composed of a piezoelectric element with a bimorph structure, and is displaced approximately perpendicularly to the recording track in proportion to the input terminal. At this time, if the reproduction signal a from the magnetic head 9 becomes small, the tracking control means 12
changes the polarity of voltage signal C. That is, the magnetic head 9
The tracking control system is configured so that the envelope of the reproduced signal a obtained from the following is maximized.

Now, when the reproduction speed command section 13 generates a command signal d for reproduction at n (n is a real number) times, the capstan motor control means 14 sends a speed sensor that detects the command signal d and the rotational speed of the capstan motor 3. 15 output signals are compared, and power proportional to the error is supplied to the capstan motor 3. That is, the magnetic tape 2 is run at a speed n times the normal playback speed. Furthermore, the command signal d from the reproduction speed command section 13 is input to the drum speed command means 16.

The drum speed command means 16 generates a command signal e at a speed (1+α·n) times the normal reproduction speed as a drum motor speed command. Here, α is a positive real number of 1 or less. The drum control means 17 compares the command signal e with the output signal of a speed sensor 18 that detects the rotational speed of the drum motor, and supplies the drum motor with electric power proportional to the error. In other words, the drum 8 is played back at the normal playback speed (l+α・n
) Rotate by 2x.

FIG. 2 is a vector diagram of the tape velocity vector of the magnetic tape 12, the velocity vector of the magnetic head 9, and the direction vector of the recording track for explaining the movable dynamic range of the head actuator 10.

FIG. 5A is a vector diagram during normal playback. Vector Vt is a tape velocity vector, and vector vh is a velocity vector of magnetic head 9. Vector vh has an angle θS. At this time, the relative velocity vector Vr of the magnetic head 9 viewed from the magnetic tape 2 has an angle θL and coincides with the direction vector Vtr of the recording track. Therefore, in this case, the magnetic head 9 follows the recording track and on-tracks without moving the head actuator 10.

Now, when performing n-times speed playback, if only the tape speed is multiplied by n, as in the conventional apparatus, the result will be as shown in FIG. 3(b). For a tape velocity vector Vto which is n times larger than the tape velocity vector Vt, the velocity vector vh of the magnetic head 9
As is clear, the relative velocity vector Vro having the angle θ"0 does not match the direction vector VLr of the recording track having the angle θ[. If the length of the recording track is Lt, then the magnetic head 9 The maximum off-track fiXo(f is Xoff=LL-tan(θro-
〇L).

On the other hand, the tracking system i1 [1vti] of the VTR of the present invention
F! Then, when playing back at n times the tape speed, set the tape speed to n times,
Since the head speed is multiplied by (10α・n), a vector diagram like that shown in the same figure (C1) is obtained. In other words, the tape speed vector VLo, which is n times larger than the tape speed vector V[, and the velocity vector vh (( Relative velocity vector Vr due to the velocity vector Vhl of the magnetic head 9 which is 1+α・n) times larger
l represents the angle θr1. The maximum off-track amount Yoff of the magnetic head 9 in this case is Yor r=t, t
-Lan(θrl-θL).

As is clear from FIGS. 3(b) and 3(c), θr1 becomes θr by the amount that the speed of the magnetic head 9 is corrected.

Therefore, Xo f f>Yo f f holds true. That is, according to the present invention, the required movable range of the head actuator 10 is smaller than that of conventional devices. Conversely, a seven-door actuator with the same movable dynamic range allows noiseless playback at higher tape speeds.

Effects of the Invention As described above, according to the VTR tracking control device of the present invention, when the magnetic tape runs at n times the speed of normal playback, the drum motor on which the magnetic head is mounted is also a capstan motor. The speed is corrected in the same polar direction as ((l+α・n) times the normal playback). Therefore, the discrepancy between the relative speed vector of the magnetic head and magnetic tape and the recording track locus does not require speed correction of the drum motor. It is relaxed compared to the case. If the dynamic range of motion of the head actuator for making the magnetic head follow the recording track is constant, the difference between the relative velocity vector of the magnetic head and magnetic tape and the recording track trajectory will be greater than that without drum motor speed correction. The speed of the magnetic tape can be increased by the amount of relaxation, making it possible to perform noiseless reproduction at higher speeds than with conventional devices.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a tracking control device for a VTR according to an embodiment of the present invention, and FIG. 2 is a diagram of a helad actuator 1.
FIG. 2 is a vector diagram of a tape velocity vector of a magnetic tape, a velocity vector of a magnetic head, and a recording track (7) direction vector for explaining a movable dynamic range of zero. 2... Magnetic tape, 3... Capstan motor, 7... Drum motor, 9...
・Magnetic head, 10...Head actuator, 11...Tracking error detection means, 12
...Tracking control means, 13...
Reproduction speed command unit, 14... Cab scan control means, 16... Drum speed command means, 17...
...Drum control means.

Claims (1)

[Claims] In a video tape recorder that has a drum motor that is equipped with a magnetic head and rotates integrally with it, and a capstan motor that runs the magnetic tape at a substantially constant speed, and performs helical scanning recording and playback on the magnetic tape, the playback speed is set to normal playback. Capstan control means for controlling the rotational speed of the capstan motor to be n times the normal playback speed when the speed is varied by n times (n is a real number); drum control means for controlling the playback speed to be (1+α·n) times the normal playback speed (α is a positive real number of 1 or less); a head actuator that is movable; a tracking error detection means for detecting the relative position of the recording track and the magnetic head from a reproduction output signal of the magnetic head; and a tracking error detection means for driving the head actuator in accordance with an output of the tracking error detection means. A tracking control device for a video tape recorder, comprising tracking control means for controlling to eliminate relative positional deviation between the recording track and the magnetic head.