JPH0369050A - Tracking control circuit - Google Patents

Abstract

PURPOSE:To prevent the width of the final track from being thinned at the time of switching from assemble to REC by adding an offset voltage to a capstan phase control system, and executing tracking so that the lower end of a video head can be coincident with the end of a recording track. CONSTITUTION:A magnetic tape, the guard bandlessly recording a recording signal obliquely onto the track by a rotary head and the four pilot signals of various frequencies are recorded to one part of the track. A reproducing device reproduces such a magnetic tape by the rotary head with gap width wider than the recording track width. The offset voltage is applied to the capstan phase control system of this reproducing device. Then, during a standby running period for consecutive recording and at the time of recording a mode succeedingly, an offset signal is supplied from an offset generating circuit 14 to an adder 10 in accordance with an error signal from a capstan phase control circuit 8 at the time of reproducing and the phase of tracking control is advanced. Then, tracking control is executed so that the rotary head can not be overlapped with the recorded track.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device suitable for editing images.

[Conventional technology]

Up to now, various discussions have been made regarding the continuous shooting of images as a basic editing function.

In a rotary head type magnetic recording/reproducing device, it is necessary for the rotary head to accurately track the track formed during recording during reproducing, and various tracking control methods have been considered for this purpose.

A common control method is a method using control signals found in 1/2-inch VTRs (video tape recorders). In this system, a control signal recorded on one end of the magnetic tape in the width direction is reproduced by a fixed head, and the rotation phase of the rotary head is controlled by this reproduction control signal. However, this method requires a separate fixed head, so 8mm! A new control method that does not use a fixed head has been adopted for JVTR. This is a method in which four pilot signals with different frequencies are circulated for each track, frequency multiplexed and recorded, and tracking is controlled so that the levels of the pilot signals obtained as crosstalk components from both adjacent tracks are equal during playback. .

A conventional example will be explained using FIG. 4. Figure 4 shows the total number of 8! The JVTH capstan control system is in trouble. In order to run the tape l by the capstan 3,
Speed control and phase control are applied. Speed control is FG
(FREQUENCY GeNeRATOR) The FG double signal from the detector is supplied to the speed control circuit 5, and the frequency-voltage converted voltage is added to the voltage from the phase control circuit 8 by the adder 9, and is supplied to the motor driver 6. Rotate the capstan motor 2. 7 is a video head;
It extracts the pilot signal along with the video signal. During reproduction, the phase control circuit 8 controls the levels of pilot signals obtained as crosstalk components from both adjacent tracks to be equal.

Switch 11 is used during recording and playback (including during assembly)
This shows the changeover switch for the phase control system of 1 when recording.
The voltage from phase control during recording in step 2 is used for control.

Figure 5 shows a pattern recorded on a tape using a video head with a track width wider than the recording track pitch. recorded in Further, FIG. 5 shows patterns before and after continuous shooting, in which phase alignment is performed in the assembled state up to pattern 25d, and the REC state is shown after pattern 25e.

During ASBL, the video head 21 is controlled so that the levels of the pilot signals obtained as crosstalk components from both adjacent tracks are equal.
The video head 21 is tracked at the center of the recording track as shown in e 25b s 25a # 25d.

When the human SBL period ends and the REC state is entered, a recording pattern corresponding to the recording track pitch is obtained from the lower end of the video head 21 as shown in . At this time, the track width 25d is narrower than the regular track width. That is, Ts > Tm (1). Furthermore, the track width of the video head is T.

Then, T becomes the following equation.

Tm = Tt (“Two Stands”) (2) However, T1: recording track width T, the last track width of the two-man SBL T: Video head track width It is.

Incidentally, related devices of this type include "Videocom" Vol. 5, No. 3, No. n (1985).

[Problem to be solved by the invention]

In the above conventional technology, since the final track of assembly becomes thin, the horizontal synchronization signal (H
synchronization signal) becomes poor, and the third
There will be a time lag caused by the formula.

K”” (3) ΔH=1α However, ΔH ΔL α to Niskew (μS) : Deviation from regular track width :Video track angle Head scan per unit length of Nidrak time, i.e. It is.

Now, if T is -22pm, the skinny amount in 8mn5P mode is 227 (μl).

That is, in the prior art, there was a problem in that skew occurred when the last location of the assembly was reproduced.

The invention aims to obviate the drawbacks of the prior art.

[Means to solve the problem]

In order to achieve the above object, an offset voltage is applied to the capstan phase control system to perform tracking so that the lower end of the video head coincides with the end of the recording track.

[Effect]

By adding an offset voltage to the error voltage of the capstan phase control system, the tracking phase is adjusted so that the lower end of the video head coincides with the recorded edge track end. As a result, a phenomenon in which the tape pattern width of the final track switching from assemble to REC does not become narrower occurs.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the capstan control system of an 8 mm IJ VTR as a whole, and the same components as in FIG. 4 are given the same numbers.

In FIG. 1, description of the operations of the same parts as in FIG. 4 will be omitted.

14 in FIG. 1 is an offset voltage generation circuit.

The switch circuit 13 determines whether or not to apply an offset voltage to the capstan phase control system. 10 is an adder.

Figure 2 shows the timing chart, and (&) indicates A.
This is the S B L (H) signal, and (b) is the offset signal from the offset generation circuit. From the moment the assembly becomes Hlgh in FIG. 2, an offset signal is added to the existing capstan phase control system by an adder 10 to control tracking.

FIG. 3 shows the head trace and tape format in ASBL and RFC with tracking control. That is, the lower end of the video head during the assembly period is coincident with one end of the lower recording track, and the last tape pattern 24d of the assembly is the first tape pattern 24d of the REC.
The tape will have a normal width without being scraped by e.

According to this embodiment, when assembling recording is performed, the final assembled track does not fit and the H arrangement becomes normal, so that no skew occurs during playback, and the quality is improved.

[Effects of the Invention] According to this embodiment, a regular track width is ensured even in assemble recording, and H (horizontal synchronization signals) are correctly aligned, so no skew occurs during playback.
Improved performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a timing chart explaining the operation of FIG. 1, FIG. 3 is a track pattern diagram obtained by the present invention, and FIG.
The figure is a conventional block diagram, and FIG. 5 is a track pattern diagram according to the conventional technique. 1... Tape 2... Capstan motor 3... Capstan 4... CFG detector 5
... Speed control circuit 6 ... Capstan motor driver 7 ... Video head 8 ... Capstan phase control circuit during playback 9 ... Adder 11 ... Switch 12 ... Phase control during REC Circuit 14...Offset generation circuit

Claims (1)

[Claims] 1. Recording signals are recorded obliquely on a track by a rotating head without a guard band, and a magnetic tape on which four different pilot signals for tracking are recorded on a part of the track is placed with a gap width wider than the recording track width. A reproducing apparatus for reproducing data using a rotary head having a phase control output means for detecting the pilot signal from the reproduced signal of the track and outputting a tracking control error signal, and a run-up period for connecting and a recording mode thereafter. At times, the apparatus further comprises means for adding an offset signal to the error signal from the phase control output means to advance the phase of tracking control, and performing tracking control so that the rotary head does not overlap a recorded track. tracking control circuit.