JPH0366054A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a magnetic recording and reproducing apparatus that performs intermittent slow reproduction.

(Prior Art) Conventionally, various slow playback systems have been devised for magnetic recording and playback devices (hereinafter also referred to as VTRs).

For example, depending on the relationship between the head used and the azimuth of the trace track, there are frame throw and field throw, etc.Depending on the tape drive method, there is a continuous slot method that drives the tape at a constant speed, and a continuous slot method that drives the tape at a constant speed, and a continuous slot method that drives the tape at a constant speed. There is also an intermittent slot system that repeats alternately. Furthermore,
Depending on the itim processing method, there is an analog slot type that reproduces and outputs the signal in real time, and a digital slot type that writes traced video information in a memory and reads it out at a predetermined timing. In VTRs of intermediate grade 81 and below, an analog intermittent slot type is generally adopted in consideration of cost, simplicity of circuit configuration, overall image quality, etc.

Incidentally, in a VTR, a capstan servo loop is configured so that the head accurately traces the pattern. The rotation of the capstan motor that runs the magnetic tape is detected by a two-phase MR (magneto-resistance) head.The MR head generates CAP/FG pulse A and CAP-FG pulse B based on the rotation speed of the capstan motor. do.

In the servo loop, based on these pulses,
A correction signal for correcting the frequency and phase is given to the capstan drive circuit to control the rotation of the capstan motor. In this way, the rotation of the capstan (travel speed of the magnetic tape) is controlled. In the intermittent slow motion type, the capstan motor is rotated intermittently to perform slow playback by repeating still images and normal images.

FIG. 6 is a timing chart for explaining slow reproduction of an intermittent slow method in a conventional magnetic recording and reproducing apparatus.

In addition, CAP-FG pulse A and CAP-FG pulse B
The pulse width is inversely proportional to the rotational speed of the capstan motor, and they have a phase difference of 90 degrees.

The standard for capstan motor drive timing is H.
-3W pulses are used. Sixth! ! 1(a), (
As shown in e), the CAP-REF signal (level Vl) which rises after a period t1 has elapsed from the rising timing of the SW pulse and further falls after a period t2 has elapsed is applied to the drive amplifier, and the drive amplifier operates as shown in FIG. (f
) is output to the motor drive circuit to start the rotation of the capstan motor. When the forced activation period 11 (high level period indicated by the period t2 of the CAP-REF signal) determined by the motor characteristics and the tape speed at constant speed has elapsed, the C signal shown in FIG. 6(d) is activated.
The AP-CONT signal starts the capstan servo loop. This results in a constant speed period, and the capstan runs at a constant speed.

Then, the constant speed period ends. That is, the brake is applied to the capstan motor to decelerate and stop the capstan motor. CTL pulses are used to determine this brake tying. That is, after the CTL pulse detection detection agent interval t3 has elapsed, the F/R shown in FIG. 6(C)
As the signal becomes L'', the CAP-
The RE signal becomes level 2. The F/R signal instructs the motor drive circuit to rotate forward and reverse. "H" of the F/R signal indicates forward rotation, and "S" indicates reverse rotation. The drive amplifier is given CAP・RE Fm@ of level V2.Thereby, the motor drive circuit is
The CAP-OLIT signal shown in > is given, and F
A reverse rotation is instructed by the /R signal, and a reverse brake is applied to the capstan motor. When the reverse brake is applied to the capstan motor, the capstan motor decelerates and the rotational speed reaches O, and further reverse rotation starts, the reverse rotation detection circuit detects the forward and reverse rotation of the capstan motor, and the reverse rotation is detected. The F/R signal becomes "H". With this, period 1! The reverse braking period indicated by lt4 has ended,
The motor drive circuit is instructed to rotate forward. Figure 6(e)
As shown in FIG.
A JT signal is supplied to drive the capstan motor.

This stops the capstan motor from rotating in reverse. At the end of the deceleration period indicated by periods t4 and t5,
The capstan motor stops and the magnetic tape stops at a predetermined position.

A still image is output while the magnetic tape is stopped, and a normal image is output while the magnetic tape is running. In this way, slow playback is performed by controlling the running and stopping of the magnetic tape.

Figure 7 shows the tape movement during the forced startup period, constant speed period, and deceleration period of slow playback, with 1liVliI on the horizontal axis and the amount of tape movement with the movement of two tracks as 100% on the vertical axis. This is a graph.

As mentioned above, a reverse brake is applied to stop the capstan motor 1 during the deceleration period, and a pulse for short-term acceleration is applied to stop the capstan motor 1 which is rotating in the forward direction. There is. However, it is difficult to reliably stop the capstan motor 1 at a predetermined stop position by only applying short-term acceleration pulses, and as shown in FIGS. After the stun motor 1 has stopped, it rotates in the opposite direction (hereinafter referred to as "rolling back").As a result of this rolling back, the magnetic tape moves in the opposite direction, as shown in FIG. It is necessary to move the magnetic tape further than the stop position by the amount of movement in the direction.In this way, the magnetic tape must be moved an extra amount to take the sway back into account, and the magnetic tape can be brought to the specified stop position. Because of this, it is not possible to obtain a good trace pattern.As a result, the level of the playback envelope (playback video 1M output) decreases, and the envelope may be missing. However, there are problems in that noise and color fading occur.

In order to reduce such deterioration of the trace pattern, there is a method of providing a capstan with a capstan brake pad and applying a mechanical brake, but this method is expensive and has poor weather resistance.

(Problems to be Solved by the Invention) As described above, in the conventional magnetic recording and reproducing device described above, when performing intermittent slow playback, the trace pattern deteriorates and noise and color fading appear on the monitor screen. There was a problem with this occurring.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a magnetic recording/reproducing device that can reduce undulation and obtain a good trace pattern.

[Structure 1 of the Invention (Means for Solving Ifli) The magnetic recording and reproducing device according to claim 1 of the present invention stops or runs a magnetic tape at a constant speed by intermittently driving a capstan motor to perform intermittent slow playback. In the magnetic recording/reproducing device, the magnetic recording/reproducing device includes: FG pulse generating means for generating an FG pulse based on the rotation of the capstan motor; a starting means for starting the rotation of the capstan motor; and a servo for driving the capstan motor at a constant speed. means for decelerating the capstan motor by applying a deceleration signal for reversing the capstan motor; reversal detection means for detecting reversal of the capstan motor by the FG pulse and outputting a detection signal; a first acceleration means for outputting a first acceleration signal for causing the capstan motor to rotate in the normal direction at a generation timing; The magnetic recording/reproducing apparatus according to claim 2 of the present invention is equipped with a second acceleration means for outputting a second acceleration signal for accelerating the magnetic tape by intermittently driving the capstan motor. A magnetic recording and reproducing device that performs intermittent slow playback by stopping or running at a constant speed, comprising: FG pulse generating means for generating an FG pulse based on the rotation of the capstan motor; and a starting means for starting the rotation of the capstan motor. servo means for causing the capstan motor to run at a constant speed; braking means for decelerating the capstan motor by applying a deceleration signal for reversing the capstan motor; and detecting reversal of the capstan motor by the FG pulse and generating a detection signal. a first acceleration means for outputting a first acceleration signal for causing the capstan motor to rotate forward at the timing at which the detection signal is generated; It is equipped with a counter that counts FG pulses, and a second acceleration means that outputs a second acceleration signal for normal rotation of the capstan motor when the count value of this counter reaches a predetermined value. be.

(Function) In the present invention, when intermittent slow regeneration is instructed, the starting means starts the rotation of the capstan motor, the servo means causes the motor to run at a constant speed, and the brake means applies a deceleration signal to decelerate the motor. Due to the deceleration of the brake means, the capstan motor decelerates and stops, and when the capstan motor attempts to reverse further, the first acceleration means outputs a first acceleration signal in response to a detection signal from the reverse rotation detection means, thereby causing the capstan motor to stop. I am trying to stop the reverse rotation. Further, the second acceleration means outputs a second acceleration signal after a predetermined period of w4, or outputs a second acceleration signal when the count value of the FG pulse reaches a predetermined value, and prevents the capstan from swinging back. Efforts are made to reduce reversal of the motor.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention.

The capstan motor 1 rotates a capstan (not shown) to move a magnetic tape (not shown). This capstan motor 1 is driven by a drive signal supplied from a motor drive circuit 2. The motor drive circuit 2 is controlled by the CAP·0LIT signal input to the VS terminal and the F/R signal input to the F/R terminal. MR head ([
A single resistance head 3 outputs a detection signal based on the rotation of the capstan motor 1. The detection signals are each amplified by an amplifier 4.5 and then sent to a Schmitt circuit (hereinafter referred to as SM) 6.
．． 7. 8M6.7 shapes the waveform of the detection signal and outputs a CAP-FG pulse B and a CAP/FG pulse A, respectively. The pulse width of the CAP-FG pulse A and the CAP-FG pulse B is inversely proportional to the rotational speed of the capstan motor 1, and the phase difference between them is 90 degrees.

CAP-FG pulse B is supplied to frequency discrimination circuit 8. The frequency discrimination circuit 8 supplies a signal based on the frequency of the CAP-FG pulse B to one input terminal of the mix amplifier 9. A phase detection circuit 1 is connected to the other input terminal of the mix amplifier 9.
The mix amplifier 9 outputs a correction signal for correcting the rotational frequency and phase of the capstan motor 1. This correction signal is applied to the drive amplifier 11 via the resistor R1 and the diode D1, and the drive amplifier 11 amplifies the correction signal and outputs the CAP-OUT signal during constant speed running to the motor drive circuit 2. The motor drive circuit 2 drives the capstan motor 1 based on the CAP/OUT signal. This servo loop causes the capstan motor 1 to rotate at a constant speed.

On the other hand, CAP-FG pulse A and CAP・FG pulse B
is also supplied to the reverse rotation detection circuit 12.

The reverse rotation detection circuit 12 detects whether the capstan motor 1 is rotating forward or reverse based on the phase difference between these pulses, and outputs a detection signal. This detection signal is given to a flip-flop (hereinafter referred to as "F") 13.

On the other hand, the input terminal 14 receives an H-8W pulse that serves as a reference for the drive timing of the capstan motor 1, and the input terminal 15 receives a CT pulse that serves as a reference between decelerations during slow playback.
L pulse is input. The H/SW pulse is given to a monostaple multivibrator (hereinafter referred to as MM) 16, which is a delay circuit.The MM16 outputs a pulse with a pulse width of tl from the rising edge of the H-8W pulse.
The output of M16 is given to MM17, and MM17 is connected to MM1.
A pulse that becomes "H" for a period tl from the fall of the output pulse of 6 is connected to the $111111 end of switch S1 and FF1
Output to B. The input end of the drive amplifier 11 is connected to a reference potential point via a diode D2, a switch S1, and a voltage 1j19, and is also connected to a reference potential point via a diode D2, a switch S2, and a voltage 820, and a switch 81 .82 is turned on, voltages Vl and V2 are applied to the drive amplifier 11.

On the other hand, the CTL pulse is given to MM21. MM21
outputs a pulse with a pulse width of t3 to the FFs 13 and 18 from the rising edge of the CTL pulse. The output of l"l"13 is F
/R signal as F/R terminal of motor drive circuit 2 and M
It is input to M22 and also to the OR circuit 24 via the inverter 23. The output of FF18 is CAP-
It is output as a CONT signal to the connection point between resistor R1 and diode D1. When the CAP・C0NT signal from the FF 18 is “L”, the output of the mix amplifier 9 is not supplied to the drive amplifier 11, and the voltage vl or voltage ■2 determined by the on/off of the switches 81 and 82 is supplied to the drive amplifier 11. Supplied.

The MM22 outputs a pulse having a pulse width of t5 to the MM25 and the OR circuit 24 from the rising edge of the F/R signal.

MM25 outputs a pulse having a pulse width of t6 to MM26 from the fall of the pulse from MM22.

MM26 outputs a pulse having a pulse width tl to the OR circuit 24 from the falling edge of the output of MM25. The output of the OR circuit 24 is applied to the control end of the switch S2. Both switches 81 and 82 are connected to the control end.
It turns on when a signal of "H" is input.

Next, the operation of the magnetic recording/reproducing II configured as described above will be explained with reference to the timing chart of FIG. 2 and the graph of FIG. 3. In addition, in Figure 3, the horizontal axis represents time, and the vertical axis represents the amount of tape movement, with the movement of two tracks taken as 100%. 2 is a graph showing the characteristics of the example device, and the broken line represents the characteristics of the conventional example.

When slow playback is specified by a user operation, first,
Forced activation is performed using the H-8W pulse as the timing basis. That is, the H◆SW pulse from the input terminal 14 is delayed by tl by M M 16 and supplied to MM17, and MM17 outputs a pulse that falls after a period t1 and a rising period t2 from the rising edge of the H-8W pulse. be done. During the “H” period of this pulse, switch S
1 is turned on, and a voltage vl is applied to the input terminal of the drive amplifier 11. From the drive amplifier 11, the CAP◆OUT signal shown in FIG. 2(f) is supplied to the motor drive circuit 2, and the motor drive circuit 2 outputs a signal for forcibly starting the capstan motor 1. This results in
The capstan motor 1 starts rotating, and the magnetic tape starts moving as shown in FIG.

The rotation of the capstan motor 1 is detected by the MR head 3. The detection signal from the MR head is the amplifier 4.5
The waveform is shaped by 8M6.7, and the waveform is
CAP-FG pulse A and CAP-FG pulse B shown in h) are generated. CAP-FG pulse B is given to frequency discrimination circuit 8. The frequency discrimination circuit 8 outputs a signal based on the rotation of the capstan motor 1 to the mix amplifier 9. A signal from the phase detection circuit 10 is also input to the mix amplifier 9, and a correction signal for servo-controlling the rotation of the capstan motor 1 is output from the mix amplifier 9. The FF 18 is given a pulse from the MM 17, and the output end of the FF 18 becomes an oven at the end of the period [1t2. As a result, mix amplifier 9
The correction signal from is supplied to the drive amplifier 11, and the drive amplifier 11 outputs the CAP-OIJT signal for constant speed rotation shown in FIG. 2(f). In this way, the motor drive circuit 2 rotates the capstan motor 1 at a constant speed (constant speed period). As a result, the magnetic tape moves at a constant speed, as shown in FIG.

Next, the end timing of the constant speed period is determined.

The CTL pulse shown in FIG. 2(b) is input to the MM21, and the MM21 transmits the pulse that falls after a period t3 based on the speed of slow reproduction from the input of the CTL pulse to the FF13, 18.
Output to. The output terminal of the FF 18 changes from oven to "off" after a period t3 from the rise of the CTL pulse.

As a result, drive amplifier 1 from mix amplifier 9
1 is blocked. Also, the F/R signal from FF3 changes from "gate" to "L". Then, the output of the OR circuit 24 becomes "H" and switch S
2 is turned on, and a CAP-REF signal having a voltage v2 is applied to the drive amplifier 11. Also, 111″
The F/R signal is also supplied to the F/R terminal of the motor drive circuit 2, and the motor drive circuit 2 is connected to the capstan motor 1.
A drive signal for reversing the motor is output to the capstan motor 1. As a result, the capstan motor 1 decelerates, and the amount of movement of the magnetic tape per unit time decreases, as shown in FIG.

In this way, the capstan motor 1 decelerates, stops, and then starts reverse rotation. The reverse rotation detection circuit 12 detects CAP-FG pulses A and C based on the rotation of the capstan motor 1.
AP/FG pulses B are given, and based on these pulses it is determined whether the capstan motor 1 is rotating forward or reverse. The reverse rotation detection circuit 12 outputs a pulse to the FF 13 at the start of reverse rotation (at the end of period t4), and the F/R signal from Fl"13 changes from "L" to "open". As a result, the motor drive circuit 2 is instructed to drive the capstan motor 1 in the normal rotation direction. The output of MM22 is “mouth” during the t5 period after the F/R signal becomes “°mouth”.
, and the output of the OR circuit 24 remains "mouth". Thus, during this period t5, the capstan motor 1 is driven to rotate in the normal direction, and the capstan motor 1 is stopped.

Furthermore, in this embodiment, the output of MM22 is MM25.
The signal is delayed by a period t6, and an output that becomes a "gate" for a period t7 from the fall of the output of the MM25 is given to the OR circuit 24 from the MM26. As a result, Fig. 2(e)
, (f), during period t7, the brake voltage v2
is supplied to the drive amplifier 11, and the motor drive circuit 2 is supplied with a CAP-OLJT signal for normal rotation, thereby driving the capstan motor 1. In this way, the capstan motor 1 swings back as shown in Figure 2 (see 1, (h)).
is suppressed.

In this way, in this embodiment, the amount of tape movement due to undulation is extremely reduced, so as is clear from the comparison between the solid line waveform and the broken line waveform in FIG. The amount of movement can be reduced.

Therefore, the tape trace pattern is good, the reproduction envelope has no missing parts, and a reproduction output corresponding to f can be obtained.

FIG. 4 is a block diagram showing another embodiment of the present invention.

In FIG. 4, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted.

CAP-FG pulse A and CAP-FG pulse B are supplied to doubler circuits 27 and 28, respectively. Double multiplier circuit 27.
28 is CAP-FG pulse A and CAP-FG pulse B
are respectively doubled and output to the OR circuit 29. OR circuit 2
The output of 9 is given to a counter 30. On the other hand, MM22
The output of the counter 3 is output to the OR circuit 24 and
It is also output to the clear end of 0.

The counter 30 is reset by the output of the MM22 and counts the output of the OR circuit 29, and when the count output reaches n,
Output the pulse to MM31. MM31 has a time constant of t7
, and provides an output of 'H'° to the OR circuit 24 for a period t7 from the rise of the pulse from the counter 30.

Next, the fifth section will explain the operation of the embodiment configured as described above.
This will be explained with reference to the timing chart shown in the figure. Figure 5 (
2 (a) to (il) respectively, and FIG. 5 (i) shows the output of the OR circuit 29.

In this embodiment, the period t6 shown in the timing chart of FIG.
is obtained from the count output of the counter 30. That is, CAP-FG pulse A and CAP-FG pulse B
are multiplied by 2 by the 2 multiplier circuits 27 and 28, respectively, and then sent to the OR circuit 2.
9 is input. The counter 30 counts the output of the OR circuit 29. When the count value reaches n, a pulse is output from the counter 30 to the MM31, and the MM31 outputs a pulse that becomes #HH for a period t7 from this pulse. This pulse turns on switch S2,
During the period t7, the voltage ■2 for forward rotation drive is applied to the drive amplifier 11.
The motor drive circuit 2 drives the capstan motor 1 in normal rotation. In this way, undulation is reduced.

[Effects of the Invention] As explained above, according to the present invention, since the sway of the capstan motor is reduced, a good trace pattern can be obtained, and the noise and color of the reproduced image on the monitor screen can be improved. Occurrence of disappearance etc. can be reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing device according to the present invention, Fig. 2 is a timing chart for explaining the operation of the embodiment, and 3v4 is a graph for explaining the operation of the embodiment. , FIG. 4 is a block diagram showing a magnetic recording/reproducing apparatus according to another embodiment of the present invention, FIG. 5 is a timing chart for explaining the operation of the embodiment of FIG. 4, and button 6
The figures are a timing chart for explaining the operation of a conventional magnetic recording and reproducing apparatus, and FIG. 7A is a graph for explaining problems in the conventional example. 1... Capstan motor, 2... Motor drive circuit, 3... MR head, 8
... Frequency discrimination circuit, 9... Fuchs amplifier, 10
... Phase detection circuit, 11 ... Drive amplifier, 12
...Reverse rotation detection circuit, 13, 18... Flip-flop, 16, 21.25.17.22.26... Mono staple multivibrator, 23... Inverter, 24... OR circuit.

Claims (2)

[Claims] (1) In a magnetic recording and reproducing device that performs intermittent slow playback by stopping or running a magnetic tape at a constant speed by intermittently driving a capstan motor, an FG pulse generating means for generating an FG pulse based on the rotation of the capstan motor. a starting means for starting the rotation of the capstan motor; a servo means for causing the capstan motor to travel at a constant speed; a braking means for decelerating the capstan motor by applying a deceleration signal for reversing the rotation of the capstan motor; Reversal detection means detects reversal of the capstan motor using pulses and outputs a detection signal, and a first acceleration signal outputs a first acceleration signal for normal rotation of the capstan motor at the generation timing of the detection signal. and a second acceleration means that outputs a second acceleration signal for normal rotation of the capstan motor after a predetermined period after outputting the first acceleration signal. Magnetic recording and reproducing device. (2) In a magnetic recording and reproducing device that performs intermittent slow playback by stopping or running a magnetic tape at a constant speed by intermittently driving a capstan motor, FG pulse generating means generates an FG pulse based on the rotation of the capstan motor. a starting means for starting the rotation of the capstan motor; a servo means for causing the capstan motor to travel at a constant speed; a braking means for decelerating the capstan motor by applying a deceleration signal for reversing the rotation of the capstan motor; a reversal detection means for detecting reversal of the capstan motor by a pulse and outputting a detection signal; and a first acceleration signal for outputting a first acceleration signal for normal rotation of the capstan motor at the generation timing of the detection signal. an acceleration means; a counter for counting FG pulses generated after outputting the first acceleration signal; and a second acceleration for rotating the capstan motor in the normal direction when the count value of the counter reaches a predetermined value. 1. A magnetic recording and reproducing device comprising: a second accelerating means for outputting a signal.