JPH0369049A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To enlarge the adjusting range of a slow tracking and to prevent the generation of a scope noise, by starting the count of an FG pulse from the detection of a control pulse and controlling a brake means with a specific timing shown by the number of this count. CONSTITUTION:By the slow reproduction instruction fed from a user a capstan error voltage is given to a motor driving circuit 4, a capstan motor starts its rotation and a magnetic tape starts its traveling. With the lapse of a specific time a servo IC2 generates a capstan error voltage based on the FG pulse fed from the motor driving circuit 4, giving it to the motor driving circuit 4, and a constant speed period results, and a system computor 1 starts the count of the FG pulse when a control pulse (CTL) is detected, completing the constant speed period based on the count number. Thus a braking period is caused and the capstan motor is stopped with decelaration. The tape stopping position can be set freely by varying the count of the FG pulse of until a braking pulse is output.

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. There are alternately repeated intermittent slot machines and one-sided slot machines. Furthermore,
Depending on the m@ 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. For mid-range VTRs and below, 1. Generally, an analog intermittent slot system is used.

Incidentally, in a VTR, a servo loop is configured so that the head accurately traces the pattern. In other words, the rotation of the capstan wheel that runs the magnetic tape is determined by the frequency generator (FG).
) has been detected. FG gives an FG pulse based on the rotation speed of the capstan to the AFC circuit.

The AFC circuit controls the capstan driver circuit and the rotation of the capstan motor based on the FG pulse. This servo loop rotates the capstan (
The running speed of the magnetic tape is controlled. In the intermittent slot one-way type, the capstan motor is rotated intermittently,
Slow playback is performed by repeating still images and normal images.

FIG. 3 is a timing chart for explaining slow playback using an intermittent slow method in a conventional magnetic recording and playback device.
FIG. 3(a) shows the =l=Yabstan error voltage input to the capstan motor driver circuit that drives the capstan motor, and FIG. 3(b) shows the tape running amount.

A cylinder switch pulse (head switching pulse) is used as a standard for the drive timing of the main 12-button motor. Based on the timing of the cylinder switch pulse, a capstan on signal is given to the 1-yabstan driver circuit, and the capstan motor starts rotating.

In this case, the full voltage determined by the limiter is applied at Pt#buskun-[-1, and the capstan speed increases (start-up period in FIG. 3). When a predetermined period of time determined by the motor characteristics and tape speed at constant speed has elapsed, the AFC circuit starts operating due to the still/slow bow, and the capstan runs at a constant speed (constant speed period in Figure 3). ).

Then, the constant speed period ends. That is, the brake is applied to the capstan, and the capstan is decelerated and stopped (brake period in FIG. 3).

A control pulse (hereinafter referred to as CTL pulse) is used to determine this brake timing.CTL
A brake pulse is applied to the capstan driver circuit after a predetermined period of time after pulse detection (hereinafter referred to as slow tracking delay amount). The capstan driver circuit then applies a reverse brake to the capstan motor to stop the magnetic tape 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.

However, from the detection of the CTL pulse, slow tracking delay m! Since the magnetic tape is stopped by outputting a brake pulse after the delay, if the amount of slow tracking delay is large, the second CTL pulse may be detected before the start of the brake period. In this case, it becomes impossible to stably advance one frame, and screen noise occurs. Therefore, the running delay (h) cannot be increased beyond a certain level.

Furthermore, since the tape speeds are close to each other immediately after starting and immediately before stopping, the CTL pulse cannot be detected sufficiently, and the stopping position of the magnetic tape is limited.

Due to the above-mentioned factors, the range in which slow tracking can be adjusted is inevitably narrowed, resulting in the problem that slow tracking may not be able to be adjusted sufficiently when playing back tapes recorded on other VTRs.

(Problems to be Solved by the Invention) As described above, the above-described conventional magnetic recording and reproducing apparatus has a problem in that the adjustment range of slow tracking is narrow and screen noise may occur depending on the recording state.

The present invention has been made in view of such problems, and includes:
Enables stable slow playback by advancing one framec
iI! In addition to preventing the generation of i-song noise,
An object of the present invention is to provide a magnetic recording/reproducing device that can prevent screen noise from occurring by increasing the amount of tracking adjustment.

[Structure of the Invention] (Means for Solving the Problems) A magnetic recording and reproducing device according to the present invention is a magnetic recording and reproducing device that performs intermittent slow reproduction by alternately stopping and running a magnetic tape at a constant speed by intermittently driving a capstan. In the recording and reproducing apparatus, a control pulse detection means for detecting a control pulse recorded in a tape running direction, an FG pulse generation means for generating an FG pulse based on rotation of the capstan, and a start rotation of the capstan. servo means for causing the capstan to travel at a constant speed; braking means for decelerating and stopping the rotation of the capstan; and counting means for counting the FG pulses by being reset by the control pulse; The starting means, the servo means, and the braking means are controlled to start the rotation of the capstan, and then the capstan is caused to run at a constant speed, and the capstan is decelerated by ~1 at a timing during the constant speed run indicated by the count number of the counting means. It is equipped with a control means.

(Operation) In the present invention, the counting means starts counting FG pulses when a control pulse is detected.The υ control means controls the braking means fir! The rotation is decelerated.As a result, the running of the magnetic tape is decelerated, and the magnetic tape stops at a position based on a predetermined count number.Therefore, the control means performs control based on the count number to reduce the speed of one frame. Slow playback of feed is performed.Also, by appropriately adjusting the setting of the count number of FG pulses to be ejected from the start of deceleration, the slow tracking adjustment range can be expanded to the entire range of slow playback.

(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 system computer 1 receives instructions from a user through an input device (not shown). Further, the system computer 1 receives not only cylinder switch pulses but also FG pulses and CTL pulses.

The system computer 91 uses the cylinder switch pulse as a timing reference and outputs a capstanmen signal, a brake signal, a still signal, etc. The main 11 knob stun on signal is a signal for starting the main 1 knob stun motor (not shown) at the same time as the timing of the cylinder switch pulse. The still/slow signal becomes 'L-1' during the constant speed period during slow playback, and starts servo control of the capstan (not shown).The still/slow signal becomes 'L-1' during the constant speed period during slow playback, and starts servo control of the capstan (not shown).
becomes. During deceleration, the brake signal becomes “)f TT” and decelerates the rotational speed of the capstan motor. CAP
-F/R signal is a signal that controls the rotation direction of the capstan motor, and when the donkey at that level rotates forward, L 11
is the time of reversal. In addition, the system computer 1 transfers data specified by the seventh code based on the user's operation to the servo IC 2.
It is output to. Furthermore, the system computer 1 has C
After the T L pulse is input, a predetermined number (corresponding to the slow tracking delay amount) of FG pulses is counted, and at this timing, the still/slow signal, brake signal, and CAP-F/R signal are set to "L". , I am trying to change my "mouth". Note that 12 FG pulses are generated in one frame period. The system computer 1 also outputs a switching signal for switching the gain of the amplifier 7, which will be described later.
Thus, the gain of the amplifier 7 is switched to the normal amplifier gain.

The servo IC 2 inputs FG pulses and CTL pulses to perform nervo control of the rotational speed (tape running speed) and phase of the nicapstan. In addition, the servo IC generates a capstan error voltage for slow playback based on the mode specification from the system computer 1, and this servo IC generates a capstan error voltage for slow playback. Given. This capstan mix amplifier 3Gt is controlled by the brake signal and still/slow signal from the system computer 1.

The motor drive circuit 4 rotates the capstan motor based on the capstan error voltage. The capstan error voltage input terminal is connected to a reference potential point via a switch 5, and the switch 5 is turned on when a capstan on signal from the system computer 1 is turned on. Further, the motor drive circuit 4 outputs FG pulses and CTL pulses to the servo IC 2 via amplifiers 6 and 7, respectively, and the gain of the amplifier 7 can be switched by a switching signal from the system combination coater 1.

Next, a second explanation will be given of the operation of the embodiment configured as described above.
This will be explained with reference to the timing chart shown in the figure. Figure 2 (
a) shows the cylinder switch pulse, FIG. 2(b) shows the capstan on signal, and FIG. 2(C) shows the still/
2(d) shows the brake signal, FIG. 2(e) shows the CAP-F/R signal, and FIG. 2(d) shows the CAP-F/R signal.
f) shows the capstan error pressure, Fig. 2 (q> shows the tape running distance, Fig. 2 (h) shows the FG pulse, and Fig. 2 (i) and (j) shows the CTL pulse. 2(k) shows the switching signal.

When slow playback is specified by a user operation, the system computer 1 sets the capstan on signal and still/slow signal to "L It" using the cylinder switch pulse as a timing reference.The capstan on signal changes to "L". Then, the switch 5 is turned off, and the capstan error voltage from the capstan mix amplifier 3 is supplied to the motor drive circuit 4. Also, since the still/slow signal is 'L11', a forced start is performed. .

That is, the motor drive circuit 4 is supplied with the high level capstan error voltage shown in FIG. 2(f), the capstan motor starts rotating, and the magnetic tape (not shown) is rotated as shown in FIG. 2(a). Start driving as shown.

Next, after a predetermined period of time has elapsed, the system combination coater 1 sets the still/slow signal to "H". Then, the servo IC 2 generates a capstan error voltage based on the FG pulse from the motor drive circuit 4 and supplies it to the motor drive circuit 4 via the capstan mix amplifier 3. This results in a constant speed period shown in FIG.

Next, the system computer 1 determines the end timing of the constant speed period. Now, assume that the system computer 1 inputs a CTL pulse (Fig. 2 (1)) at the timing of the F pulse of the FG pulse shown in 21m(h). It starts counting FG pulses from , and ends the constant speed period based on the count number. In the example of FIG. At this time, the still/slow signal and CAP-F/R signal are set to "L Tl" and the brake pulse is set to "mouth".This causes the braking period, and the main 11 bustan error voltage occurs, not shown in Figure 2 (f). Then, the capstan motor decelerates and stops.In other words, the number of FG pulses counted from the detection of the CTL pulse becomes the slow tracking delay amount.

In this embodiment, one frame feeding is adopted, and the end of the braking period is determined by counting the FG pulses for one frame period from driving to stopping. In this way, the system computer 1 sets the -1-yabstan on signal, still/slow signal, and CAP-F/R signal to "low" at the timing of the 1G pulse and sets the brake signal to "L" to shorten the braking period. Terminate it.

Thereafter, the above-described operations are repeated to perform slow playback. By changing the number of FG pulse counts (slow tracking delay amount) until the brake pulse is output, the tape stop position can be set freely. Therefore, as shown in FIG. 2 (j), even if the CTL pulse detection timing is during the braking period, the tape stop position can be freely set by appropriately setting the number of G pulses to be counted. I can do it.

In addition, when a CTL pulse is output immediately after tape drive or just before the tape stops, the system computer 1 outputs a switching signal "tobi" to the amplifier 7, changes the gain of the amplifier 7, and detects the CTL pulse. Note that even when reproducing a tape in which CTL pulses are temporarily missing, stable operation is possible by counting FG pulses.

In this way, in this embodiment, the system computer counts the FG pulses from the detection of the CTL pulses to determine the timing of the brake operation, so that the tape stop position can be stabilized. Furthermore, by appropriately setting the count number of FG pulses, the adjustment range of slow tracking can be expanded to cover the entire range, and the stop position can be freely set. Furthermore, since the amplifier gain is switched between t and immediately after driving and just before driving, CTL pulses can be detected at any timing.

[Effects of the Invention] As explained above, according to the present invention, the control means determines the control timing of the brake means based on the count number of the counting means that counts the FG pulses.
The magnetic tape can be reliably stopped at a predetermined position.
Slow playback is possible with stable one frame advance. Furthermore, the slow tracking adjustment range can be expanded to cover the entire slow playback range.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a timing chart for explaining the operation of the embodiment, and FIG. 3 is a conventional magnetic recording/reproducing apparatus. 3 is a timing chart for explaining slow playback of . 1... System computer, 2... Servo ICl 3... Capstan mix amplifier, 4... Motor drive circuit, 7... Amplifier.

Claims (1)

[Claims] 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, there is provided a control pulse detection method for detecting control pulses recorded in the tape running direction. means for generating an FG pulse based on the rotation of the capstan; starting means for starting the rotation of the capstan; servo means for driving the capstan at a constant speed; a brake means for decelerating and stopping the FG; and a brake means that is reset by the control pulse to stop the FG.
a counting means for counting pulses; and the starting means;
control means for controlling a servo means and a brake means to cause the capstan to run at a constant speed after starting rotation, and to decelerate the capstan at a timing during constant speed travel indicated by a count number of the counting means; A magnetic recording/reproducing device characterized by comprising: