JPS60137184A - Frame feed reproducing device - Google Patents

Abstract

PURPOSE:To perform frame feed reproduction without using a control signal by controlling an electromechanical transducing element with the signal obtained by processing a tracking error signal in rotary head type VTR. CONSTITUTION:When a frame feed command is inputted, a switch 27 is closed synchronizing with a head switch signal and a track change command is outputted to a tracking error detecting circuit 21. Further, a command for rotating a capstan at a low speed is sent out to a capstan motor driving circuit 29. Tracking control is carried out during a low-speed tape run only by controlling heads A and B. When the mean value of control quantity of the heads A and B decreases gradually to the value before the frame feeding, zero is recognized and detected by a zero detecting circuit 28 to stop the capstan motor 30. Therefore, the reproduction in which frames are fed, one by one, securely is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a frame-advance playback device for a magnetic recording and playback device (hereinafter simply referred to as a VTR). The present invention relates to a frame-advance playback device for a VTR that can generate noise due to an electro-mechanical conversion element.

Conventional structure and its 113J Problem Conventionally, the frame-by-frame playback method in a rotary head type VTR is, for example, in a VH3 type VTR, frame-by-frame playback is performed using a control signal recorded on the control track at the frame timing. ing.

j7z That is, when the head generates the vertical blanking part -tS, be sure to turn the capstan motor 1. This is a method in which the tape is turned on hard and the tape advances two tracks (one frame), and when two tracks progress is detected by the control signal, the brake is applied to the capstan motor to bring it to a sudden stop, thereby eliminating noise on the screen. It is a blue R-1L with brake control, timing control, etc. of the capstan motor.
However, in recent years, various methods have been proposed to perform tracking control without using the full control pressure. A pilot signal for tracking control is superimposed and recorded using the same head as the magnetic head used for recording.Therefore, since there is no control signal in VTRs of these types, the same frame-by-frame playback as before is performed. It is possible to do this, but we need to come up with a new method.

OBJECTS OF THE INVENTION The present invention provides a novel frame-advance-11'' production device [L] that does not use control signals and does not generate noise.

Structure of the Invention Does the present invention have a tracking system? In this method, a tracking error signal is obtained by recording a pilot signal of 1 lil along with a video signal and processing the pilot signal that is reproduced. When a frame feed command is input, the electro-mechanical transducer moves the magnetic head by the equivalent of one frame during the non-contact period with the tape, and the electricity applied to the electro-mechanical transducer is The tape is driven at a low speed until the average value of M (for example, voltage) becomes approximately zero.

DESCRIPTION OF EMBODIMENTS Before detailed description of the present invention, a method of creating a tracking error signal using a pilot signal will be described. The method for creating a tracking error signal using a pilot signal varies from one type of pilot signal to four types.
God's methods have been proposed up to the fiIi type, but
Since the tracking error signals obtained in either method have the same form, the present invention can be applied to methods for creating multiple tracking error signals. Here, a four-frequency pilot signal method using pilot signals of four types will be explained as an example.

In FIG. 1, At, B4. A, B,...
. . , □ are each recording track recorded on the magnetic tape by the A head and B head. Arrow a indicates the scanning direction of the rotary head. In each recording track, each pilot signal indicated by f, to f4 is sequentially recorded in one field along with the video signal. The recording order of pilot signals circulates in the order of fl + f2 + fs + f4, and f
After 4, fl is recorded. Within each field period, the pilot signal is recorded with a fixed uniqueness. The frequency of the pilot signal can be set to the values shown in Table 1, for example. In Table 1, fH indicates the frequency of horizontal synchronization 4E">j in the video signal, and 6.5 fH indicates a frequency that is 6.5 times the frequency of the horizontal periodic signal.Table 1 Each recording track The frequency difference of the pilot signals between
As shown in the figure, the frequency is fH or 3fH.

When the head scans the track Ai (1==1, 2...), the frequency difference between the pyrolot signal of the scanning track and the pyro signal recorded on the adjacent track on the right side on the paper is It is fH, and the one on the left is always 3fH. The 0 head is Bi (i=1,2...
...) When scanning a track, the relationship is reversed to that described above, and the frequency difference between the pilot signals between the scanning track and the adjacent track on the right is always 3fH, and that on the left is always fH.
It is H.

Since the pilot signal is a relatively low frequency signal near 100KllZ, the pilot signal recorded on the adjacent track can be reproduced as a crosstalk signal without the head scanning over the adjacent track. +! /
1) The head is on track with A2) rack and ρ) is the main scanning signal obtained when the head is f3.
．． f2. The synthesis of f4 is No. 1, f3 has the highest level, and then f, , f are played back at the same level.The head moves from track person 2 to track B.
When the reproduction scan is performed with a shift to the 2 side, the level of the reproduction pilot signal obtained is f3°i4. It becomes smaller in the order of t2.

On the other hand, if the head scans with a deviation to track B1 (!), the pilot signals generated become smaller in the order of f3, f2, and f4. By extracting the difference signals fH and 3fH from the pilot signal in advance and comparing the reproduction levels of both signals, it is possible to know the amount and direction of deviation of the head from the main scanning track.

Figure 2 shows tracking error 11. FIG. 2 is a block diagram of a reproducing circuit for removing lees. Terminal 1 in Figure 2
A signal in which the video signal and the pilot signal have been combined is input. Circuit 2 is a low-pass filter that extracts only the pilot signal from the combined reproduced signal.

The pilot signal obtained at this time is a composite signal of the main scanning track and other pilot signals recorded on both adjacent tracks. The circuit 3 is a balanced modulation circuit, which multiplies the above-mentioned composite pilot signal by the reference signal 4g supplied from the terminal 4. The reference signal supplied from terminal 4 supplies the same frequency as the pilot signal recorded on the main scanning track. For example, 2 in Figure 1,
When the head performs raw scanning on track A2, the input signals to the balanced modulation circuit 3 are f2., f3.
It is. Therefore, the output signal of the balanced modulation circuit 3 is f2゜f3
．． Signals having the sum and difference frequencies of each signal of f4 and the signal of f3 are output. Circuit 5 is a tuned amplifier circuit tuned to the fH signal, and circuit 7 is a tuned amplifier circuit tuned to the 3fH signal. Circuits 6 and 8 are amplitude detection rectifier circuits,
Circuit 9 is a level comparison circuit. Therefore, each pilot toy number δ extracted as a crosstalk signal from both adjacent tracks is extracted as a difference signal with the pilot signal recorded on the main scanning track, and then the level comparison circuit 9 detects the level difference. The signal corresponding to
It is retrieved at 0. As for the signal obtained at the terminal 16, when the reproduction level of fH is higher than the reproduction level of 3fH, a potential of ■ corresponding to the level difference is taken out, and in the opposite case, a potential of ○ is taken out. Since the signal outputted to the terminal 10 includes information on the amount and direction of track deviation of the head, it can be used as a tracking error signal.

However, tracking error signals that are actually suitable for practical use require a lot of processing.As is clear from FIG. fH or 3fH) are opposite to each other.

For this reason, an analog inverting circuit 11 and a switch 12 are used when the head scans the track B and B.
It is sufficient to invert the signal at the terminal 10 analogously when scanning the rack. That is, the terminal 14 switch 1s17uL is connected to Ai) Uy/scan 1j, +1 Ni beam 11; and Bi) Rack scan 11. ′
I and C are connected to the output of the analog inversion circuit 11. As a result, in the output calculation of terminal 14, Ai
, Bil゛The head should scan regardless of the rack.
If it deviates to the right from the rack, the potential ■ is always applied, and if it deviates to the left, the potential θ is applied. Therefore, terminal 1
The tracking error signal obtained in step 4 can be used to control the displacement of the capstan motor and magnetic head.
The head can always be scanned on-track on the main scanning track.

The above is an outline of the method for obtaining a tracking error signal using four types of pylon signals.

The present invention provides a novel frame-by-frame advance method by attaching a magnetic head to an electro-mechanical transducer and controlling this electro-mechanical transducer using a signal obtained by processing the tracking error signal as described below. l') It provides raw equipment. Hereinafter, details of embodiments of the present invention will be discussed.

FIG. 3 is a circuit block diagram showing approximately 1'lt'+ of an embodiment of the present invention, in which a tracking error detection circuit 21 outputs a tracking error signal from a 1') raw signal from the magnetic head 20. The circuit 22 is a comparison circuit,
The tracking error signal is compared with the head control signal, and a signal for correcting the head control signal is output.

That is, if the tracking error signal is thicker than the head control signal, the head control signal is increased by a minute amount, and in the opposite case, the head ilj control signal is increased by a minute amount. The circuit 23 is a one-frame delay circuit, and receives as input the output signal of the one-frame delay circuit 23, the output signal of the comparator circuit 22, and the head control amount of 1 near 7 (2 track pitches) via the switch 27. The i-signs from the data signal generation circuit 26 are added together and inputted. 71, the output of the delay circuit 23 is returned as its own human power, and is also traced through the drive circuit 24 as a head control signal to drive the electro-mechanical conversion element 25 to convert it to the electro-mechanical conversion element 1iiJ. 25
The magnetic head 20 attached to the disk is displaced in a direction perpendicular to the longitudinal direction of the entire recording trajectory. Furthermore, the delay circuit 230
It is also input to the "zero detection υ" circuit 28.

By controlling the electromechanical transducer 26, the present invention
A control system whose sole purpose is to perform tracking control by maintaining the tracking error signal, J>vvc at a constant level, is constructed.The timing diagram in Figure 4 shows how to perform frame-by-frame playback using this configuration. This will be explained using both.

In the frame-advance playback VC, when a frame-advance command is input, switch 2 is closed in response to a head switching signal, and a track change command is output to the tracking error detection circuit 21. That is, in FIG. 1, the heads are A1 and B,
) The reference key signals f1 and f2 are changed to f3 and f4 in order to change from the state in which the rack is being scanned to the state in which the rack is scanned in A, . . . B2). When a frame feed command is input manually, in addition to performing the above-mentioned operations, a command is output to the capstan motor drive circuit 29 to rotate the capstan at a low speed. This low-speed rotational operation of the capstan is detected by the zero detection circuit 28 using the electro-mechanical conversion element 25.
It continues with the dwarf, where the average voltage applied to becomes zero.

That is, in FIG. 4, when a frame-instruction command is input, the switch 27iONl is activated in the next frame, and the 2nd head and B head are each advanced one frame (two tracks) to A in the next frame. The switch 27 is ON only for one frame, and after that, when the closed OA and B heads advance one frame, the tracking error detection circuit 21 advances the capstan motor by the maximum one frame. Rotate at low speed to run the tape. Since the tape runs at a low speed, tracking control is performed only by controlling heads A and B without applying any control to the capstan. This is possible because the tape transition is slow, so the position of the head and tape (corresponding to tracking error) does not change suddenly. When tracking is performed by moving heads A and B while the tape is running at a sluggish pace, the average value of the control amount of heads A and B gradually decreases over a finite period of time (the tape actually advances one frame). The area will be the same as before the frame-by-frame advance (time required). This value is set as zero, and the zero detection circuit 28 detects the value. When zero is detected, the carburetor stan motor will stop. This completes the frame advance operation. Thereafter, by inputting the frame-by-frame advance command again, the frame-by-frame advance can be performed, and by inputting the frame-by-frame advance command repeatedly in the same way, continuous frame-by-frame advance playback is possible as slow motion playback.

The electro-mechanical transducer used in this example may be, for example, a piezoelectric element or an electromagnetic-mechanical transducer, but it is not desirable to apply a DC voltage to these for a long time due to the characteristics of the element. I'd be damned if I didn't have it. Therefore, as shown in this embodiment, it is necessary to stop the tape running when the average value (DC component) of the amount of electricity applied to the element becomes zero.

Unfortunately, in this embodiment, two heads play adjacent tracks. I explained so-called frame playback, where two heads play the same track.
The same is true in the case of so-called field reproduction, and in particular in this case, the two heads have the same waveform before they are controlled, so the DC component of the control amount for each head can be made zero.

In addition to the embodiments described above, the present invention can also implement similar processing by software using a microcomputer or the like.

Effects of the Invention As is clear from the above description, the present invention provides a novel method that enables noise-free frame-by-frame playback without using conventional control signals. Extremely large.

Furthermore, according to the present invention, the control of the capstan for performing frame-by-frame feeding can be done roughly at 1V), and the conventionally used brakes: 1ill + TII,
Timing: (It does not require precise control such as i-control, and the conventional method can easily realize playback that reliably sends only one frame, even during Tanabata, without requiring any precision.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the recording magnetization locus according to the 4-frequency pilot Ib method, Fig. 2 is a circuit block diagram for obtaining a dragging error, and Fig. 3 is a diagram of a frame-by-frame playback device of the present invention. A circuit block diagram showing the embodiment, FIG. 4 is a timing diagram showing the timing of each part in FIG. 7... Tuned amplifier circuit, 6, 8...
... Amplitude detection rectifier circuit, 9 ... Level comparison circuit, 2Q ... Magnetic head, 21 ... Tracking error detection circuit, 22 ... Comparison circuit , 23...1 frame delay circuit, 24...
・Drive circuit, 25...'Electro-mechanical conversion element 2
6...1-frame data signal generation circuit, 28...
...Zero detection circuit, 29 ...Capstan motor drive circuit, 3o ...Capstan motor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] Using a rotating head, a pilot signal is recorded on the magnetic tape as a group of inclined discontinuous recording tracks, and a pilot signal is superimposed on the information signal. In a magnetic recording internal generation device in which a tracking error signal is obtained based on a level difference between reproduction crosstalk signals of pilot signals recorded on front and rear recording tracks, the mechanical position of the rotary head is determined by an electro-mechanical conversion element. The device includes means for displacing the recording track in the width direction of the recording track, and after the electro-mechanical transducer completely equalizes the displacement T1 corresponding to one frame on the head, tape transport is started at a low speed, and the electro-mechanical transducer starts moving the tape at a low speed. A frame-by-frame playback device characterized in that the tape transport is stopped when the average value of the amount of electricity applied to the conversion element becomes approximately zero.