JPS62239357A - Information signal reproducing device - Google Patents

Abstract

PURPOSE:To detect completely the control abnormality of a tracking control means from a fact that the prescribed one of two types of frequency components related to the differential frequency between pilot signals of two continuous adjacent tracks is detected from the output of a mixing means. CONSTITUTION:Reference signals have frequencies f1, f4, f3 and f2 while a rotary head is tracking the control target tracks of frequencies f1-f4 recorded in a control pull-in state. Then a 2fH component is produced when the tracks where frequencies f2 are f4 are recorded are traced. While the reference signals have frequencies f3, f2, f1 and f4 while the head is tracing the tracks where frequencies f1-f4 are recorded and if the head is tracing the position shifted from the control target track 2 by-track pitches. Then a 4fH component is produced when the tracks where frequencies f1 and f3 are recorded are traces. Thus the 2fH component is produced when a tracking error is less than 1-track pitch; while the 4fH component is produced when the tracking error exceeds 1 the track pitch respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an information signal reproducing device, and particularly to a recording device in which four types of pilot signals having mutually different frequencies are sequentially recorded on each track along with an information signal in a predetermined rotation. The present invention relates to a device for reproducing a pre-P information signal from a medium.

<Prior Art> As this type of device, a type that performs tracking control using a 1i4 frequency system has been proposed and implemented in, for example, a video tape recorder (VTR) that records and reproduces video signals on a magnetic tape. There is.

The tracking control using the above-mentioned four-frequency method will be briefly explained below.

In this one set, fle f2 t f 3 a f
Pilot signals having four different frequencies are recorded in each trunk in the order of 4, and a tracking error signal is formed by comparing the pilot signal levels reproduced from both adjacent tracks of the track to be controlled during reproduction. There is.

As a specific method, first, each frequency fjrf2*
Set fsmf4 to f2-fl=f, -f4=fH
(fl is the horizontal scanning frequency of the video signal) fl - f2
=f4-f1=3fi, and for the pilot signal component reproduced by the video signal reproducing head, a reference signal having the same frequency as the pilot signal recorded in the controlled track or adjacent to the controlled track is applied. Multiply by a reference signal of the same frequency as the pilot letter recorded on the truck.

For example, when the frequency of the pilot signal recorded on the controlled track changes from f1 → f2 → f3 → f4,
The frequency of the reference letter to be multiplied is f1 → f2 → f3
→ f4 or f1 → f4 → f3 → f2 is a common method.

As a result, one of the pilot signal components reproduced from both adjacent tracks of the track to be controlled can be converted into an i'Hfl component, and the other can be converted into a 5fH component. These fH acid components and 3f
A tracking control signal can be obtained by comparing the H components and determining whether the output is positive or negative by 7J'x.

<Problems to be solved by the invention> By the way, V that performs tracking using the four-frequency method as described above
Various methods have been proposed for shifting the track to be controlled by two tracks in order to speed up the interval between control pull-in segments in TR. This uses, for example, the level of the tracking error signal described above and the level of the fH acid component 3fi component described above to detect that the playback head is tracing a position that is off by one track pitch or more from the track to be controlled, and The reference signal was generated by shifting Rochi Silane by two locations.

However, since the above-mentioned tracking error signal is originally a signal formed for tracking control, even if this level increases, it may cause the immediate playback head to trace a position that is off by one track pitch or more from the track to be controlled. It does not indicate that This is fH
The same applies when using the acid component 5fH component.

Therefore, conventional discrimination of this type requires a certain amount of time and has not yielded great results. Furthermore, there is a risk of malfunction if the linearity of the recording track is impaired for some reason.

In addition, in recent years, in addition to the conventional standard track pitch recording/playback mode (referred to as SF), the trunk pitch has been narrowed to enable long-time recording and playback - ζ= -2=, +-
t-/Ma'T5'L-Takushi-S'1 44
d= /% WQt) J? Atm has been adopted, but as a result of this, it has become necessary to determine the recording trunk pitch. Conventionally, the tracking error signal, 3f[component, and fH acid component have been used to determine the track pitch, but there are similar problems such as the determination takes too much time and there is a possibility of malfunction.

The present invention has been made in view of the problems typified by the above,
It is an object of the present invention to provide a signal reproducing device that can detect control abnormalities in tracking control more quickly and accurately.

<Means for Solving the Problems> With this object in mind, according to the present invention, the pilot signals of the 4S class having mutually different frequencies are sequentially recorded for each trunk along with the information signal in a predetermined first low-chie line. A device for reproducing the information signal from a recording medium in which the reference signal having the same frequency as the pilot signal of the 48th category is rotated in the opposite manner to the rotation of the 141 for each period related to the rotation period of the rotary head for reproduction. means for mixing the output of the reproducing rotary head and the output of the generating means;
Means for performing tracking control using the frequency component of 213IF related to the frequency of the difference between the pilot signals of adjacent tracks in the output of the mixing means; Based on the fact that the predetermined one is detected from the output of the mixing means,
A configuration is adopted that includes means for detecting a control abnormality of the tracking control means.

<Operation> By configuring as described above, it is directly detected that the tracking has deviated by one track pitch or more, so that tracking control abnormality can be detected reliably.

<Example> Examples of the present invention will be explained below.

FIG. 1 is a diagram showing the configuration of a reproduction system of a VTR as an embodiment of the present invention. The VTR of this embodiment wraps the tape around a rotating cylinder over an angular range of 180° + α0, and traces the tape with two rotating heads with a phase difference of 180°, thereby detecting the area corresponding to 180°. The recorded video signal for one field is reproduced as the time-base compressed audio signal recorded in the portion corresponding to α0. When used as an audio-only device, play back any of the time-axis compressed audio signals recorded on each channel obtained by dividing (180 + α) 0 by α0 by n + (n is an integer of 2 or more). do.

In the operation section 45, whether to perform playback as a VTR or
AV switching information indicating whether to perform playback as an audio-only device and channel information indicating which channel to start playback from when performing playback as an audio-only device are manually determined.

The channel designation circuit 46 determines from which channel the audio is to be played based on the information obtained from the operation section 45, and when the operation section 45 commands to use it as '7TR, it selects a predetermined end. Specify the channel.

3 is a terminal to which a 50Hz rectangular wave (hereinafter referred to as 30PG) synchronized with the rotational phase of the rotary heads 1 and 2 having a phase difference of 18o0 is input, and the gate signal generator 47 uses this 30PG to generate a desired signal. Generates gate signals for gate circuits 42 and 45 so that audio signals are reproduced from the channels. The time-base compressed audio signal passed through the gate circuits 42 and 43 is sent to the PCM audio signal processing circuit 4.
4, the signal is subjected to processing such as time axis expansion and error correction, and then output as audio output.

Also, if you use it as a VTR! The video signal output from the switch 39, which is switched by l0PG, undergoes well-known signal processing in a video signal processing circuit 40, and then is output as a video output.

A low pass filter (LPF) 6 is for separating a pilot signal included in the reproduced signal, and the separated pilot signal is supplied to a multiplier 7. A reference signal having the same frequency as the four types of pilot signals described above is supplied to the multiplier 7 in the order of f4→f3-+f2→f1→f4 while being switched every one field period. The output of the 4-frequency generator 8 is supplied to the selection switch 49, and is multiplied in the above order from the logic level combination K of 50PG and a signal obtained by dividing the 30PG by % by the rising edge detection circuit 10 and the flip-flop (FF) 12. It will be supplied to the container 7.

As is well known, the output of the multiplier 7 is supplied to a 3fi band pass filter (BP?) 13 and an fH BPF 14, and each frequency component is detected by a detection circuit 15, 16 and then compared in level by a comparator 17. Well, the tracking error signal (
ATF signal). Since only the ATT signal formed from the pilot signal of the channel being reproduced is effective at this time, the sample and hold (8/H) circuit 50 sounds at the timing when the designated channel is being traced. At this time, the sound is generated by calculating the logical sum of the gate signals for heads 1 and 2 using the OR gate 51, and detecting the falling edge of the monomulti 52, which is triggered by the rising edge of the output of the OR gate 51, using the falling edge detection path 53. formed by h
% pulses. For example, the monomulti 520 time constant is set to fall after a period during which the head makes (α/2) 0 rotations after being triggered.

The added ATF signal is mixed in an adder 20 with a tape speed control signal supplied from a tape speed control circuit 21, and is supplied to a tape running control circuit 22 to perform tracking control.

Here, the principle of detection of control abnormality in this embodiment will be explained. If the tracking control is now in the control pull-in state, the control target track is fl If2#f3#f
The frequency of the reference signal when the rotating head traces the recorded trunk of 4 is f1*, respectively.
fJ t '3 * f2, and a 2fH component is generated when tracing the track where f2tf4 is recorded. Assuming that the Nakaman head is tracing the position shifted two trunk pitches from the control target trunk, '
1 e f2 e f5 * The frequencies of the reference signals when the rotary head traces the track where fJ is recorded are f3, f2, fl, fJ and ■, respectively.
, fl, and f3 are recorded, a 4fi component is generated. Here, the 2fl component generally occurs when the tracking error is less than one track pitch, and the 4fH component generally occurs when the tracking error exceeds one track pitch. However, when performing so-called azimuth overwriting, it is necessary to consider the difference between the track pitch and the head width. Therefore, when detecting a tracking error of one track pitch or more, it is sufficient to detect whether the arH component contained in the output signal of the multiplier 7 exceeds a predetermined threshold level.

24 is 2fH B'P? And this BP? 24 is level detected by a detection circuit 26 and compared with the aforementioned threshold level by a comparator 27. If there is a tracking error of one track pitch or more, a high level signal is outputted from the comparator 27. The threshold level of this comparator is determined by the overwriting element described above.

This information on the presence or absence of a tracking error of one track pitch or more is valid only when it is formed from the pilot signal of the channel being reproduced, so this comparator 2
The output of 7 is gated with the above-mentioned % pulse by an AND gate 54.

The operation of shifting the controlled track by two tracks using the output of the AND gate 54 and the 8P-LP switching operation will be described below.

FIG. 2 is a timing chart for explaining the switching operation of the track to be controlled in the VTR shown in FIG. When , the reference signal becomes fs, and the AND gate 54 executes the fear pulse. From this K, FF via OR gate 11
12 is triggered and the reference signal is generated Low take 1
The key is shifted two steps. As shown in the figure, this quickly brings the tracking control into the pull-in state. Note that the reproduced pilot signal in Figure 2 is obtained only at the timing when the designated channel is being traced.
In the figure, for the sake of simplicity, the figures are shown as if they were obtained over the entire period.

Next, the operation when an attempt is made to reproduce a track recorded in 8P on an LP will be explained using Fig. 1g5. In this case, the 4fH component is output from the multiplier 7 once every 8 fields. At this time, the tend gate 54 gates the % pulse, and the rotation ratio η of the reference signal is shifted by two, and the FF 55 is set. Along with this, F
The Q output of F55 becomes high level, and the AND gate 57
inputs the edge pulse output from the 30PG edge detection circuit 56 to the CK terminal of the counter 58. When the counter 58 counts 8 edge pulses, the Q
The output is set to high level and the FF55 is reset. Therefore, the FIF 55 outputs as shown in FIG. 3, but if the trunk recorded in the SP is played back in the LP, the 4fi component is output again from the multiplier 7 after 4 field periods, and the AND gate 54 outputs the % pulse. gate. This 4 HALS is further gated by an analog gate 59 and supplied as a speed error pulse to the speed side control circuit, thereby switching the tape running speed from the LP speed to the SP speed.

If a track recorded in LP is to be reproduced in BP, four pulses will be output from the AND gate 59 to the same machine, and the tape running speed will be switched from the 8P speed to the LP speed.

In the VTRK as described above, the 4 output from the multiplier 7
By detecting the fi release, tracking errors of one trunk pitch or more can be detected accurately and quickly, and this is effective in reducing control pull-in time and improving the accuracy of 13P-LP switching. be.

Although the above-mentioned VTR detects the 4fl component, if the characteristics of the comparator 17 are reversed, it is possible to detect a tracking error of one track pitch or more by detecting the 2fH component.

<Effects of the Invention> In addition to the above-described aspects, according to the present invention, tracking control abnormalities can be detected more quickly and accurately, and accordingly, information signal reproduction that can quickly bring the tracking control state into a good state is possible. The equipment is in the book.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a VTR as an embodiment of the present invention, FIG. 2 is a timing chart for explaining the switching operation of trunks to be controlled in the VTR of FIG. 1, and FIG. 12 is a timing chart for explaining the tape speed switching operation at the 11521st V'rR. In the figure, 1 and 2 rotary heads, 3 are 50PG input terminals, and 6 is an LP for separating the reproduced pilot signal. . 7 is a multiplier, 8 is a reference signal generator, 15 is 5f
BPF that separates l components, 14 is f, BPIF that separates components, 17 is a comparator, 2o is an adder, 21
2 is a speed control circuit, 22 is a tape running control circuit, and 24 is a 4
BPF for separating fi components, 27 is a comparator, 54
d end gate, 55d flip-flop, 59 is an AND gate.

Claims (3)

[Claims] (1) An apparatus for reproducing an information signal from a recording medium in which four types of pilot signals having different frequencies are sequentially recorded along with the information signal for each track in a predetermined first rotation, means for generating a reference signal having the same frequency as a pilot signal in a second rotation that is opposite to the first rotation for each period related to the rotation period of the reproducing rotary head; and an output of the reproducing rotary head and the means for mixing the output of the generating means, means for performing tracking control using two types of frequency components related to the frequency difference between pilot signals of adjacent tracks in the output of the mixing means, and pilot signals of adjacent tracks. An information signal reproducing device comprising means for detecting a control abnormality of the tracking control means based on the fact that a predetermined one of two types of frequency components related to the difference frequency is detected from the output of the mixing means. (2) The information signal reproducing apparatus according to claim 1, wherein the generation rotation of the reference signal by the generating means is shifted based on the detection output of the detecting means. (3) The information signal reproducing apparatus according to claim (1), wherein the moving speed of the recording medium is switched based on the detection output of the detection means.