JPH03154255A - Magnetic tape driving device - Google Patents

Abstract

PURPOSE:To keep the speed of a magnetic tape constant and to attain high speed feeding by applying drive control to a drive motor of a winding reel base based on a detection output of a winding diameter detection circuit for a magnetic tape roll at the high speed fast forward reproduction mode. CONSTITUTION:Number of revolutions of supply and winding reel bases is detected respectively by frequency generators 18, 19 and its output signal is inputted to a winding diameter detection circuit 20. The circuit 20 obtains a ratio of number of revolutions of each reel to obtain a radius of the winding tape roll. The output of the circuit 20 is given to a speed reference voltage generating circuit 21 to generate a speed reference voltage corresponding to the winding diameter detection value. Moreover, the output of the generator 19 is compared with the reference voltage at a speed comparator circuit 23 to obtain an error signal of a speed system. An output reproduced by a control head 8 is inputted to a phase control circuit 10 to receives an error signal of a phase system. Both error signals are inputted to a mixer circuit 12, from which a mixer signal is inputted to a motor drive circuit 13 which controls a drive motor 17 thereby controlling the carrier speed of a tape 3 to be a control value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a magnetic tape drive device used in a magnetic recording and reproducing device (referred to as VTR), and is particularly effective for fast-forwarding and rewinding reproduction of a magnetic tape. related to equipment.

(Prior Art) FIG. 2 shows a block diagram of a drive control device for a capstan motor during fast-forward playback of a conventional VTR.

As shown in the figure, a capstan shaft 1 is rotationally driven by a capstan motor 4. As shown in FIG. The magnetic tape 3 is transferred in the direction of the arrow by this pressure contact between the capstan shaft 1 and the pinch roller 2. Then, a frequency signal corresponding to the rotational speed obtained by a frequency generator 5 directly connected to the capstan shaft 1 is inputted to the speed control circuit 7 via the first frequency divider 6, and the capstan motor 4 is rotated. Obtain the error signal of the speed control system according to the number.

Further, the output obtained by reproducing the control signal recorded on the magnetic tape 3 by the control head 8 is inputted to the phase control circuit 10 via the second frequency divider 9, and the reference signal generation circuit 11
The error signal of the phase control system with respect to the control signal of the magnetic tape 3 is inputted to the mixing circuit 12 to obtain a mixed signal, which is inputted to the motor drive circuit 13 to drive the capstan motor 4. By doing so, the speed of the magnetic tape 3 is controlled to be constant.

(Problem to be Solved by the Invention) In the capstan motor drive control device configured as described above, in order to make the fast forward playback speed N times the magnetic tape speed during recording, the number of revolutions of the capstan motor 4 must be N. However, since the diameter of this capstan shaft is extremely small, there is a limit to the possible range of increasing the rotation speed of the capstan motor and increasing the magnetic tape speed by N times.
There was a problem that high-speed fast-forward playback of magnetic tapes was not possible. In view of this problem, the present invention focuses on the fact that the diameter of a pair of magnetic tape reel stands is larger than the capstan shaft diameter. It is an object of the present invention to provide a magnetic tape drive device capable of high-speed fast forward playback and rewind playback within a controllable rotational speed range of the drive motor of the take-up reel stand.

(Means for solving problems) The present invention solves the above problems and achieves the objectives.

reel stand driving means for rotating at least one of a pair of reel stands that engage with and rotate integrally with a pair of reel ribs around which magnetic tape is wound in a direction in which the magnetic tape is wound;
means for detecting the rotational speed of the pair of reel stands; means for detecting the winding diameter of the magnetic tape wound on the pair of reel stands, which receives the output of the rotational speed detection means as an input; a speed reference voltage generation means set from the output of the detection means; a frequency/voltage conversion means that receives as input the output of at least one of the rotation speed detection means of the pair of reel stands; and the output of the conversion means and the speed reference voltage. The apparatus is characterized in that it comprises a speed comparing means which receives the output of the generating means as an input, and obtains a speed-related error signal to control the reel stand driving means.

(Function) The present invention controls the rotation speed of the take-up side reel stand of a pair of reel stands having a diameter larger than the capstan shaft diameter, so that even at the same rotation speed, the magnetic tape transfer speed due to the rotation of the reel stand is faster. This allows fast-forward playback and rewind playback of the magnetic tape.

Furthermore, the present invention controls the rotational speed of the reel stand by mixing an error signal with one phase difference in addition to the speed-related error signal, thereby locking noise during magnetic tape playback and operating the magnetic tape in a stable state. be able to.

(Embodiment) FIG. 1 shows a block diagram of a magnetic tape drive device according to an embodiment of the present invention during high-speed fast-forward playback.

In the figure, 14 is a supply side reel stand for the magnetic tape 3;
15 is a rotating cylinder, 16 is a reel stand on the winding side of the magnetic tape 3, 17 is a drive motor for this reel stand on the winding side, 18
19 is a frequency generator that detects the rotation speed of the supply side reel stand 142 and the take-up side reel stand 16; 20 is a frequency generator 1;
8.19 output n1lpn? By inputting and finding the ratio of nt/ng, the radius of the magnetic tape roll on the winding side R? 21 is a circuit that generates a speed reference voltage value corresponding to the winding diameter detection value of the winding diameter detection circuit 20; 22;
23 is a frequency/voltage conversion circuit that receives the output of the frequency generator 19 as an input, and 23 is a speed comparison circuit that compares the output voltages of the frequency/voltage conversion circuit 22 and the speed reference voltage generation circuit 21 to obtain a speed-related error signal. , circuits 22 and 23 constitute a speed control circuit 24.

In addition, the control head 8. The second frequency divider 9° phase control circuit 10 and the reference signal generation circuit 11 constitute a phase system control circuit, which includes a motor drive circuit 13 for the drive motor 17 of the take-up reel stand 16, and the speed system and phase system. The circuit 12 for mixing the thumbtack difference signals is the same element as that shown in FIG. 2, so the explanation thereof will be omitted.

Next, the operation of this embodiment during high-speed fast-forward playback will be explained.
The magnetic tape 3 is transferred from the supply reel stand 14 to the rotating cylinder 1.
5 and is wound onto the take-up reel stand 16. The take-up reel stand 16 is rotated by a drive motor 17 whose rotational speed is controlled by a motor drive circuit 13.

The rotational speeds of the supply side and take-up side reel stands are detected by respective frequency generators 18 and 19, and their output signals are input to the winding diameter detection circuit 20.

Here, the sum of the cross-sectional areas of the magnetic tape rolls wound around both reel stands 14 and 16 of the magnetic tape 3 is constant.

7C(R11"-rl")+π(Ry"-rl")=K
l (constant) --- (1) However, R, ... supply side magnetic tape roll radius r, ... both reel hub radius R1 ... take-up side magnetic tape roll radius, R,'' +R,”=, (constant)+2r,”...
・・・・・・・・・・・・・・・(2) Also, the circumferential speeds of both magnetic tape rolls are equal.

R,・n,=R,・n.

However, n,... Number of rotations of the supply side reel stand n, r...
・Rotation speed of the reel stand on the take-up side From equations (2) and (3) above, (3) Therefore, in the 1-reel diameter detection circuit 20, n 1 / n
By determining the ratio of g, the winding side magnetic tape roll radius R? can be found.

The output of the winding diameter detection circuit 20 causes a speed reference voltage generation circuit 21 to generate a speed reference voltage value corresponding to the detected value of the diameter of one winding.

Further, the output of the frequency generator 19 of the take-up reel stand 16 is input to a frequency/voltage conversion circuit 22, where the frequency is converted into voltage, and together with the speed reference voltage value of the speed reference voltage generation circuit 21, the speed comparison circuit 23. The voltages are compared in this speed comparison circuit to obtain a speed-related error signal.

Here, the transport speed V of the magnetic tape 3 is.

V=2π・R1・R7・・・・・・・・・・・・・・・
・・・・・・・・・・・・(6) Therefore, in order to keep ■ constant, n2=2(constant)/2πR1...
It is sufficient to generate the speed reference voltage so as to satisfy (7).

Next, the output obtained by reproducing the control signal recorded on the magnetic tape 3 by the control head 8 is inputted to the phase control circuit 10 via the second branching device 9, and the reference signal generation circuit 11
Obtain the error signal of the phase system with respect to the reference signal from .

The speed system and phase system thumbtack difference signals obtained in the above manner are inputted to the mixing circuit 12 to obtain a mixed signal, which is inputted to the motor drive circuit 13, which drives the drive motor 17 of the take-up reel stand 16. By controlling the drive of the magnetic tape 3, the transport speed of the magnetic tape 3 can be controlled to be constant.

In the embodiment described above, the input signal of the speed control circuit 24 is only the output of the frequency generator 19 of the take-up reel stand 16, but it is also possible to use the output of the frequency generator 18 of the supply reel stand 14. It's okay.

Also, although the speed reference is supplied to the speed comparison circuit 23 as a voltage value, the same effect can be obtained even if the frequency/voltage conversion circuit 22 is replaced with a digital frequency/voltage conversion circuit and the offset value (initial value) is changed. is obtained.

Further, in this embodiment, for convenience of explanation, phase system control using control signals from the reproduced magnetic tape is also added, but it is also possible to control the speed of the magnetic tape to be constant using only the speed system.

(Effects of the Invention) As explained above, the present invention controls the rotation of the drive motor of the take-up reel stand based on the detection output of the winding diameter detection circuit of the magnetic tape roll diameter during high-speed fast forward (rewind) playback. This allows high-speed fast forwarding (rewinding) while keeping the magnetic tape speed constant within the rotational speed control range of the drive motor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic tape drive according to an embodiment of the present invention during high-speed fast-forward playback, and FIG. 2 is a block diagram of a capstan control device of a conventional magnetic tape drive during fast-forward playback. 3... Magnetic tape, 8... Control head, 9... Second frequency divider, 10... Phase control circuit, 11... Reference signal generation circuit, 12... Mixing circuit, 13 ...Motor drive circuit, 14... Supply side reel stand, 15... Rotating cylinder, 16... Take-up side reel stand, 17... Take-up side reel stand drive motor,
18.19... Frequency generator, 20... Winding diameter detection circuit, 21... Speed reference voltage generation circuit, 22...
- Frequency/voltage conversion circuit, 23...speed comparison circuit. 24...Speed control circuit.

Claims (2)

[Claims] (1) a reel stand driving means that rotates at least one of a pair of reel stands that engage with a pair of reel ribs around which a magnetic tape is wound and rotate integrally in a direction in which the magnetic tape is wound; means for detecting the rotation speed of the paired reel stands;
means for detecting the winding diameter of the magnetic tape wound on the pair of reel stands, which inputs the output of the rotation speed detecting means; a speed reference voltage generating means set from the output of the winding diameter detecting means; A frequency/voltage conversion means that receives as input the output of at least one of the rotation speed detection means of a pair of reel stands, and a speed comparison means that receives as input the output of the conversion means and the output of the speed reference voltage generation means, A magnetic tape drive device, characterized in that the reel stand drive means is controlled by obtaining a system error signal. (2) A means for detecting a control signal recorded on a magnetic tape, and a phase control means for comparing the phases of the output of the means and the output of the reference signal generating means to obtain a phase system error signal, as claimed in claim 1. (1) A magnetic tape drive device characterized in that a reel stand drive means is controlled by mixing the speed system error signal as described above.