JPS6276042A - Signal reproducing device - Google Patents

Abstract

PURPOSE:To obtain a signal reproducing device attaining the automatic discrimination of a track pitch accurately at recording quickly by comparing a tracking error signal obtained in a different timing. CONSTITUTION:A tracking error signal is subject to sampling and holding by S/Hs 12, 13 respectively in two different timings on one field and the result is inputted to a differential amplifier 15 to obtain the level difference between the two levels. When the level difference is nearly zero, the tape speed is coincident with that at the recording and when the difference is large,the tape speed differs from the speed at the recording. Then the level difference is compared with a prescribed value Vref making allowance for an error in the track linearity at comparators 16, 17. The output is inputted to a OR circuit 18 and a low signal when the tape speed at the reproduction is matched with that at the recording and a high signal when different is outputted to a terminal 19. Thus, the tape speed is discriminated automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for reproducing a recorded signal from a recording medium on which recording is performed by selectively setting a plurality of types of track pitches.

[Conventional technology]

In a magnetic recording/reproducing device using a rotary helical scan method such as a household VTR, a synchronizing signal of some kind is recorded on the magnetic tape during recording, and this synchronizing signal is reproduced during playback to control the rotational phase of the capstan. A servo circuit performs tracking control so that the rotary head correctly traces the video signal recording track on the magnetic tape.

The synchronization signal is usually a control signal (hereinafter referred to as C
A method is used in which a ten-cycle pulse signal of a vertical synchronizing signal called a TL signal is written on the end of the tape.

In the system using this control signal, it is easy to automatically determine and switch the speed recorded on the magnetic tape during recording.

As an example of conventional automatic discrimination means using this CTL, there is an example of a frequency
There is a method in which the number of pulses of the CTL signal is counted as the period of the CTL signal, and the recorded speed is determined based on the counted value.

[Problem that the invention seeks to solve]

In the case of the above-mentioned conventional method using a CTL signal, there is a problem that it cannot be applied to another servo method, which is a method in which a synchronization signal is superimposed and recorded on a video track, such as the well-known four-frequency method. there were.

The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a signal reproducing device that does not require a CTL signal and can quickly determine the track pitch with a simple configuration.

[Means for solving problems]

The signal reproducing device according to the present invention performs recording by comparing tracking error signals obtained at different timings for the same track of a recording medium recorded by alternatively setting two or more types of trunk pitches. This system is configured to determine the track pitch.

[For production]

In the configuration described above, if tracing is not performed at the same pitch as the track pinch during recording, the comparative output of the tracking error signals obtained at two different timings will be different, so the recording track pitch of the recording medium can be determined. It is.

〔Example〕

Figures 1 and 2 are diagrams for explaining a VTR as an embodiment of the present invention, and show a mode (hereinafter referred to as SP) in which recording and playback is performed at a standard tape speed, and a mode in which recording and playback is performed at a +7 tape speed. 2 of the mode (hereinafter referred to as LP) that performs
This will be explained by taking as an example a VTR that performs tracking control in a so-called 4-frequency system, in which the speed can be set and four types of conventionally used pilot signals with different frequencies are cyclically superimposed and recorded on a video signal for each track. .

Incidentally, the frequencies of the four types of pilot signals in the four-frequency system are f, f2. f3. f4 is set to the following value. That is, f, -f2=fH, f, -f
4=3fH, f3-f4==fH, f3 f2=3f
H, where fH is the horizontal scanning frequency.

FIG. 2 shows the SP recording pattern and the LP recording pattern superimposed, and as is clear from the figure, the SP recording pattern and the LP recording pattern have different track inclinations. Therefore, it can be seen that when reproduction is performed at a tape speed different from the tape speed at the time of recording, the tracking error signal changes linearly with respect to a change in position within one field when the same trunk is controlled.

In the VTR of this embodiment, the recording speed is automatically determined by detecting a change in the tracking error signal within this 1 field.

FIG. 1 shows a block diagram of a track pitch discrimination circuit in a VTR as an embodiment of the present invention. In Fig. 1, 1, 10, 14, and 19 are terminals, 2 is a low-pass filter (LPF), 3 is a multiplier, 4 is a local pilot signal generation circuit, and 5 is a band-pass filter (BPF) that separates the signal of frequency fH. ), 6 is a BPF that separates a signal with a frequency of 3fH, 7.8 is a detector, 9 and 15 are differential amplifiers, 11 is a timing signal generation circuit, 12 and 13 are sample and hold circuits (S/H), 16, 17 is a comparator, and 18 is an OR circuit.

In the discrimination circuit configured as described above, a reproduced signal in which a video signal and a pilot signal are superimposed is input from terminal 1, and only the pilot signal component is separated by BPF 2. Next, the multiplier 3 generates the separated reproduced pilot signal component and fl generated by the local pilot signal generation circuit 4.

f2. Multiply by a local pilot signal having a frequency of f, , f4. The output signal of the multiplier 3 is supplied to BPFs 5 and 5, and only frequency components of fH and 3fH are extracted. These fH and 3fH components are signals related to tracks adjacent to the trunk being traced by the magnetic head, and these signals are detected by the detector 7.
, 8 and input it to a differential amplifier 9, information on the amount and direction of track deviation of the magnetic head can be obtained. Since the details are well known, their explanation will be omitted.

Next, this tracking error signal is transmitted to S/H12 and S/H12, respectively, at two different timings within one field.
Sample and hold is carried out by 13. Numbering pulses at these timings are generated by a timing signal generation circuit 11 in response to a head switching signal from a terminal 10.

The two timings may be arbitrary timings within one field. A signal from one S/H 12 is connected to a capstan control circuit through a terminal 14 to control the capstan.

Further, the signals sampled and held at two timings are input to the differential amplifier 15, and the level difference between them is determined. It is clear from FIG. 2 that if this level difference is close to zero, the tape speed is consistent with that during recording, and if it is significantly different, it is incorrect.

Therefore, comparators 16 and 17 compare the level difference mentioned above with a certain value Vref obtained by reading errors such as track linearity, and input the output to the OR circuit 18. If the tape speed matches that at the time of recording, a low signal is output; if not, a high signal is output.

This allows the tape speed to be automatically determined.

In this embodiment, two types of track pitches can be set. However, even if there are three or more types, it is possible to distinguish between them by sequentially switching the tape feed speed during playback between these three types. be.

〔Effect of the invention〕

As described above, the present invention has the effect of providing a signal reproducing device that can quickly and accurately automatically determine the track pitch during recording with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a trunk pinch and discrimination circuit in a VTR according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing SP/LP recording patterns in the VTR according to the embodiment of FIG. . In the figure, 2 is a low-pass filter (LPF), 3 is a multiplier, 4 is a local pilot signal generation circuit, 5, 6
is a band pass filter (BPF), 7.8 is a detector, 9
, 15 is a differential amplifier, 11 is a timing signal generation circuit,
12.13 is a sample hold circuit (S/H), 16.
17 is a comparator, and 18 is an OR circuit.

Claims (1)

[Claims] In a device that reproduces a recorded signal from a recording medium recorded by selectively setting a plurality of track pitches, the track pitch can be determined by comparing tracking error signals for the same track obtained at different timings. A signal reproducing device characterized in that it discriminates.