JPH0732635B2 - Intermittent drive type magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermittent drive type magnetic recording / reproducing apparatus (hereinafter referred to as an intermittent drive type VTR), and particularly to a method for correcting the rotational drive amount of a capstan motor in the apparatus. It is about.

[Conventional technology]

FIG. 4 is a block diagram of the intermittent VTR which the applicant of the present invention has already developed. In the figure, the magnetic tape 1 is sandwiched between the capstan shaft 2 and the pinch roller 3, and the magnetic tape 1
Is driven at a constant speed by the rotation of the capstan shaft 2. A motor drive circuit (MOTOR DRIVE AMP .; hereinafter referred to as MDA) 7 is connected to the capstan motor 4.
The rotation of the capstan motor 4 driven by the MDA 7 is transmitted to the pulley 5 via the belt 6. An angle sensor 8 is directly connected to the capstan shaft 2, and the angle sensor 8 detects a rotation angle of the capstan shaft 2, that is, a rotation distance and generates an angle signal. Further, the capstan shaft 2 is provided with a brake 9 for braking the rotational movement thereof, and the brake 9 is generally a mechanical brake with which a felt or the like comes into contact. The angle sensor 8 is connected to the error detector 11 via the position detector 10, and the feed amount setting circuit 12 is also connected to the error detector 11. The position detector 10 detects an angle signal and detects a position of the capstan shaft 2, that is, a movement amount to generate a position signal. The feed amount setting circuit 12 sets an intermittent feed amount of the tape. A set movement amount signal is generated. In addition, the error detector 11
Is for detecting the difference between the position signal and the set movement amount signal and generating an error signal. In addition, the feed amount setting circuit
12 is an intermittent drive signal generation circuit 13 and an error detector
11 is directly connected to MDA7. The intermittent drive signal generation circuit 13 generates a timing signal for intermittently driving the motor 4 according to the set movement amount signal So.

Next, the operation of this apparatus will be described with reference to the operation waveform chart of FIG. Now, in this apparatus, the intermittent drive signal generation circuit 13, MDA7, and capstan motor 4 are driven based on the set movement amount signal So set by the feed amount setting circuit 12. Here, the above-mentioned set movement amount signal So is 1 to 1 shown in FIG.
Powering is commanded during the 10th pulse, and braking is commanded during the remaining 11th to 16th pulses. Actually, the output voltage of the MDA 7, that is, the applied voltage of the capstan motor 4 is as shown in FIG. 5 (a), and as described above, the capstan motor for the power running operation is in the period of the 1st to 10th pulses. The forward rotation is performed, and the capstan motor reverse rotation is performed as the braking operation during the period of the 11th to 16th pulses.

When the capstan motor 4 rotates in this manner, the capstan shaft 2 is rotated by the belt 6 and the pulley 5, and the magnetic tape 1 is moved by the pressing action of the pinch roller 3. The state of the tape speed at that time is shown in FIG. At the same time, when the capstan shaft 2 rotates, the angle sensor 8 integrated with the capstan shaft 2 operates. As a typical example of the angle sensor 8, there is one in which three optical sensors are arranged on the circumference of a flywheel (not shown), and the waveform of the angle signal which is the output of these three is shown in FIG. As shown in (c), there are three angle signals C1, C2, C3. By applying these three angle signals to the matrix circuit, a pulse signal as shown in FIG. 5 (d) can be obtained. The number of these pulse signals is the amount of movement of the capstan shaft 2, that is, the position of the magnetic tape 1. Will be shown. This position signal is compared with the set movement amount signal set by the feed amount setting circuit 12 by the error detector 11.

Further, FIG. 5 (e) shows a drum pulse generator (not shown).
Is generally called an FF pulse and is a reference pulse for adjusting the phase of the drum. By this pulse and the video head writing pulse (Fig. 5 (f)), writing is performed at the position of the arrow in the figure. The timing is set. The FM video signal is actually written by the video head in one frame period (1/30 sec) from this timing to. This is shown in FIG. 5 (g). That is, a signal as shown in FIG. 5 (g) is written on the magnetic tape 1 intermittently (every few seconds), and finally recorded continuously.

That is, as shown in the magnetic pattern diagram of FIG. 6, after the recording of one frame is completed, the tape stands still for several seconds, and then,
The next frame is written, but in recording these, a fairly advanced technique was required to write so that there would be no gap between them and vice versa. Therefore, as shown in FIG. 5 (d), powering is performed during the 1st to 10th pulses and braking is performed during the 11th to 16th pulses, but the rotation angle of the capstan shaft 2, that is, the tape. The amount of movement of is usually not determined in accordance with the set value due to the moment of inertia of the capstan system. For example, if the capstan shaft 2 rotates too much, as shown in FIG.
The second pulse is generated, and if the next frame is written as it is, a gap is generated between it and the previous frame. Therefore, if a pulse other than 16 is detected by the error detector 11,
A correction voltage as shown by the solid line 20 or the broken line 21 in FIG. 5A is applied to the capstan motor 4 via the MDA 7. That is, when the number of pulses is 16 or more, a negative voltage (reverse voltage) is applied to the capstan motor 4 as shown by the solid line 20, and when the number of pulses is 16 or less, a positive voltage (forward forward voltage) is applied to the capstan motor 4. , The capstan motor 4 reverses,
Normal rotation is corrected. The amount of movement at this time is minute.

[Problems to be solved by the invention]

In such a conventional device, a normal intermittent operation can be performed by the above operation, considering only the initial time, that is, the time of factory shipment. That is, the correction voltage can be adjusted before shipment so that there is no gap or overlap between the frames and continuous frame recording is possible.

However, in the VTR that causes the intermittent recording or reproducing operation, a brake is required to apply a sudden braking to the capstan shaft 2. As described above, this brake applies the felt pad to the outer surface of the flywheel. It is customary to Therefore, the braking force fluctuates over time, and even if satisfactory performance was obtained at the initial stage as in the conventional method, it could not be maintained for a long period of time. That is, in the conventional method, the pulse becomes 15 pulses or less due to the change of the contact pressure of the brake with time, and even if the positive correction voltage is applied, it is insufficient and the magnetic tape pattern is overwritten, or conversely. The number of pulses is 17 or more, and even if a negative correction voltage is applied, it is insufficient and often causes a gap. In the case of a long-time VTR whose main purpose is for monitoring, it is usually operated only in a playback mode when an accident occurs, so that it is normally operated only for several months. Therefore, long-term reliability and performance stability are strongly required.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional ones, and an object thereof is to provide an intermittent drive type magnetic recording reproducing apparatus capable of performing stable intermittent recording for a long time.

[Means for solving problems]

An intermittent drive type magnetic recording / reproducing apparatus according to the present invention comprises a feed amount setting means for setting an intermittent feed amount of a capstan motor, a feed amount detecting means for detecting an actual feed amount of the capstan motor, and the detected feed amount detecting means. When the feed amount of the step is different from the set feed amount of the step,
A correction signal generating circuit for generating a pulse signal having a polarity, the number, and an amplitude value according to the error signal and correcting the rotational drive amount of the capstan motor at the step is provided.

[Action]

In the present invention, after driving the capstan motor by a predetermined amount, an error between the actual feed amount of the capstan motor of the step and its set feed amount is detected, and the capstan motor of the step of the step is detected according to the error. The rotation drive amount is finely controlled by a pulse signal to always perform optimum intermittent feed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a block diagram of an intermittent drive type VTR according to an embodiment of the present invention. The difference from the block diagram of the conventional device shown in FIG. 4 is that a new motor drive amount is provided between the error detector 11 and MDA7. The correction signal generation circuit 14 is connected to improve the reliability of the intermittent recording operation. The motor drive amount correction signal generation circuit 14 is a circuit that generates a pulse signal by changing the polarity, the number, and the amplitude value of the pulse according to the error signal.

Next, the operation will be described.

The magnetic tape 1 is sandwiched between a capstan shaft 2 and a pinch roller 3, and is fed by a certain distance according to the rotation of the capstan shaft 2. Intermittent drive signal generation circuit 13 during intermittent drive
A timing signal S1 for more power running operation and braking operation is generated and given to MDA7. Then, the capstan motor 4 rotates in response to the output signal of the MDA 7, the rotation is transmitted to the pulley 5 via the belt 6, the capstan shaft 2 rotates, and the capstan shaft 2 is directly connected and attached. A flying flywheel (not shown) rotates. This flywheel has a plurality of sets of recesses and protrusions on its circumference, and the angle sensor 8 is sandwiched between the recesses and protrusions.
Is installed. Generally, an optical sensor is used as the angle sensor 8. In this embodiment, three pairs of a light emitting element and a light receiving element are used and fixed at positions where the waveforms of the angle signals C1, C2 and C3 shown in FIG. 2 are obtained. Then, the rotation angle of the capstan shaft 2 is detected by the three angle signals from the angle sensor 8, and the three angle signals are given to the position detector 10. The position detector 10 detects the amount of movement of the magnetic tape 1 based on these signals and generates a position signal S2. During intermittent driving, the position signal S2 is constantly detected, that is, the magnetic tape 1 moves while detecting the amount of movement. At the completion of the powering operation and the braking operation, the error detector 11 detects the difference between the feed amount setting signal S3 and the position signal S2 and generates an error signal S4.

In the present embodiment, the output signal of the motor drive amount correction signal generation circuit 14 is changed according to the polarity error signal S4 to change the torque of the capstan motor 4 so that the timing at the time of recording can be adjusted against the load fluctuation. It is possible to stabilize intermittent operation by eliminating misalignment and tape slack.

Here, considering the conventional method again, for intermittent recording
If the brake gradually loosens and the load becomes lighter during long-term operation with the VTR, the capstan shaft 2 will rotate from the predetermined target position, and it will not stop due to the braking action during the 11th to 16th pulses, The 17,18, ... th pulse is generated. Therefore, it becomes necessary to apply the maximum negative power to the capstan motor 4 by the correction signal and reverse the rotation. That is, since the initial driving force is greatly deviated, it must be corrected again, and the overall error becomes large. In terms of the whole operation, after a large forward rotation, the reverse rotation center and the braking surface slide again from both sides, leading to further unstable operation. This causes tape slack. If the brake becomes harder and the load becomes heavier during a long-term operation, the capstan shaft 2 will not advance to a predetermined target position. In this case as well, the same correction as above will be repeated and the tape It causes looseness.

Therefore, in the apparatus of this embodiment, the following correction is performed. That is, when the brake 9 becomes loose, an error signal S4 is generated from the error detector 11, and this error signal S4 is added to the motor drive amount correction signal generation circuit 14 to generate the error signal S4 at 11-16 in FIG.
Even after the braking action in the period of the th pulse signal is finished, as shown in FIG. 2 (a), four thin pulses in the negative direction are generated with a predetermined amplitude. This pulse signal is applied to MDA7 as it is, and a braking action, that is, a motor reverse action is exerted. At this time, the pulse level and the number of pulses are changed according to the magnitude of the error signal S4. In general, it is desirable that this part be constructed by employing a small-scale microcomputer of about 4 bits.

Therefore, the drive voltage applied to the capstan motor 4 in time series is as shown in FIG. As an example, t1, t2, and t3 are shown, but the amplitude value, the number of pulses, and the number of steps can be arbitrarily selected and designed by the microcomputer, but it is not enough if the material of the brake pad is selected. It doesn't have to be complicated.

In the above embodiment, the case where the brake is loose has been described, but when the brake is hard and strong, the motor drive pulse voltages t'1, t'2, t'3 become high as shown in FIG. Increase the starting torque.

According to such an embodiment, even if the state of the brake changes with time and temperature / humidity changes, a minute correction is performed when the one-step capstan motor rotates.
Regular tape feeding is performed. Therefore, as shown in FIG. 6, after one frame is recorded, the next frame is continuously recorded without any gap or overlap. That is, in this embodiment, stable intermittent recording is performed,
Intermittent video information can be recorded on the magnetic tape in the same format as continuous recording.

〔The invention's effect〕

As described above, according to the present invention, in the magnetic recording / reproducing apparatus for intermittently driving and recording / reproducing the capstan motor, the magnetic recording / reproducing apparatus responds to the error signal between the preset feed amount of the capstan motor and the actual feed amount. Since a circuit for minutely controlling the rotational drive amount of the step of the capstan motor is provided, it is possible to stably obtain a desired feed amount even with a change due to a long life such as a brake,
The effect is that optimum intermittent feeding can always be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of an intermittent drive type VTR according to an embodiment of the present invention, FIGS. 2 and 3 are operation waveform diagrams of the VTR, and FIG.
FIG. 5 is a block diagram of an intermittent drive type VTR already developed by the applicant, FIG. 5 is an operation waveform diagram thereof, and FIG. 6 is a diagram showing a magnetic tape pattern when continuous intermittent recording is performed. 4 ... Capstan motor, 7 ... Motor drive circuit (MD
A), 10 ... Position detector, 11 ... Error detector, 12 ... Feed amount setting circuit, 13 ... Intermittent drive signal generation circuit, 14 ... Motor drive amount correction signal generation circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An intermittent drive type magnetic recording / reproducing apparatus for intermittently driving a capstan motor for recording / reproducing, wherein a feed amount setting means for presetting a feed amount of one step of the capstan motor, A feed amount detecting means for detecting the feed amount of one step of the capstan motor, and an error for detecting an error between the detected feed amount of the step and the feed amount of the step set by the feed amount setting means. And a correction signal generation circuit for generating a pulse signal having a polarity, the number, and an amplitude value according to the error detection output to correct the rotational drive amount of the capstan motor for the step feed. An intermittent drive type magnetic recording / reproducing apparatus characterized by the above.