JPS6292260A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain smooth reproduction by multiplying a regenerated pilot signal and a reference signal supplied at the first half of a reproducing area to form a tracking control signal and multiplying the pilot signal with a reference signal supplied at the latter half to form a recording speed discriminating signal. CONSTITUTION:A band pass filter (BPF) 1 extracts only a pilot signal from a reproducing signal 100 and gives it to a balanced modulator 2. The modulator 2 multiplies the pilot signal with a reference signal 200 from a reference signal oscillator 3, a BPF 4 extracts a signal of frequency fH only and a BPF 5 extracts a difference signal of frequency 3fH. The frequency of the signal 200 is made different in the first half (l) and the latter half (m) of the reproducing area where the same pilot signal is recorded and the result is fed to the modulator 2 and a difference frequency component 1300 for the tracking control is obtained from the first half (l) and the component 1300 for recording speed discrimination is obtained from the latter half (m) by a comparator 8. Thus, the adverse effect of the signal for recording speed discrimination on the tracking control signal is reduced to apply excellent tracking control and recording speed discrimination.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic recording and reproducing apparatus that performs tracking control and recording speed discrimination using a four-frequency pilot signal.

[Technical predecessor of the invention] Recently, a difference frequency signal (
There are some that perform both tracking control and recording speed determination based on the error signal).

[Problems with the Background Art] When reproducing a normal video signal with such a magnetic recording/reproducing device, the video track is 16.6 times the time.
Since it has a long length of 8 m5ec, even if tracking control and recording speed determination are performed on the same track in a time-sharing manner, there is sufficient margin to allow each section to be set arbitrarily to some extent. However, when recording and reproducing signals in very small sections, such as in a multi-PCM audio system in which a normal information track is divided into multiple channels and PCM audio signals of multiple channels are recorded, tracking control and recording speed discrimination are required as described above. If both (Jf) are used, the effect of transient response will occur, and it may be difficult to use both together. For example, in the above multi-PCM audio system,
As shown in FIG. 4, when the tracks are divided into 1 to 6, and both the above-mentioned recording speed determination and tracking control are to be performed in each track, that is, in a minute section,
The following problems arise.

Divide each track in Figure 4 into two and use the first half for speed determination.
The latter half is used for i~ racking control, and by applying a reference signal corresponding to the pilot signal reproduced from these sections during reproduction and performing ti)i, two types of external frequencies fH13fH as shown in Fig. 5 are converted to F. ? Ru. In FIG. 5, the broken line indicates the detected value of the imaging width, and if the time constants of the attack and recovery times of detection are long, the signal for speed determination will get stuck in the area for 1 to racking. If tracking control is performed in such a state, the tracking control cannot be performed properly due to the influence of the speed determination signal, resulting in tracking deviation or loss of control.

Therefore, in order to avoid this drawback, it is possible to shorten the attack and recovery time of the signal for speed determination, but if this is made too short, there will be problems with detection during steady state, and it is impossible to shorten it. There was a problem.

[Object of the Invention] In view of the above-mentioned drawbacks, an object of the present invention is to provide a magnetic recording and reproducing device that can smoothly perform recording speed discrimination and tracking control based on a pilot signal reproduced from a minute section. is.

[Summary of the Invention] The present invention records both a pilot signal and an information signal whose frequencies change cyclically, and performs tracking control and recording speed determination based on a difference frequency signal obtained by multiplying the reproduced pilot signal by a reference signal. In a magnetic recording/reproducing device that performs the above, the same pylon 1~ signal is recorded in the reproduction area for 2 minutes v1, and different frequency standards are used for the pilot signal obtained in the first half and the pilot signal obtained in the second half. The above object is achieved by multiplying the signals and using the difference frequency signal obtained from the first half for tracking control and the difference frequency signal obtained from the second half for recording speed determination.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention. Band pass filter (BPF) 1 is A,
Only the reproduced pilot signal is extracted from the reproduced signal 100 1q received from the B head (not shown) and outputted to the balanced modulator 2.

The balanced modulator 2 has pQj supplied from the reference signal oscillator 3.
The signal 200 is multiplied by the input reproduced pilot signal, and the result is output to a bandpass filter 4 that extracts only the frequency fH and a bandpass filter 5 that extracts only the difference frequency signal of the frequency 3fH. The pilot signal of frequency fH extracted by bandpass filter 4 is detected by detector 6 and then input to the positive input terminal of comparator 8 . Further, the pilot signal with a frequency of 3fH extracted by the bandpass filter 5 is detected by the detector 7, and then
It is input to the negative input terminal of comparator 8. The comparator 8 outputs a difference signal component 1300 between the two inputted detection signals to the terminal a of the switch 9, and a signal whose polarity is inverted by the inverter 10 to the terminal A of the switch 9. At the same time, the two detected signals are input to the sample and hold circuit 13. Switch 9 is timing generator 1
According to the polarity switching signal 300 generated at J:1, the terminals are switched to the a and b sides, and an error signal 400 is generated.

This error signal 400 is input to the sample and hold circuit 12. The sample-and-hold circuits 12 and 13 receive the difference signal component 1 by the sample-and-hold timing signals 500 and 600 supplied from the timing generator 11, respectively.
300, the error signal q4oo is sampled and held, and the sample and hold circuit 12 holds the sample and hold value 700.
is output to a cylinder phase and speed control system (not shown).

The sample hold circuit 13 has its sample hold value 8
00 is output to the waveform shaping circuit 14.

The speed determination logic circuit 15 determines the recording speed of the tape currently being played based on the waveform shaping signal 900 obtained from the waveform shaping circuit 14, and outputs the determination result.

The timing generator 11 inputs a head switching pulse 1000 and a track area signal 1200, outputs a sample hold timing signal 500.600, and outputs a signal 5e11.2 to the reference signal oscillator 3.

The reference signal oscillator 3 receives input clocks 1100 and S
ej! A reference signal 200 is generated based on the 1.2 signal and outputted to the balanced modulator 2.

Next, the operation of this embodiment will be explained in detail according to the timing chart of FIG. FIG. 2(A) shows a head switching pulse 1ooo, whose period is 2T1. Second
Figures (B), (C), (D) Track area signal 120
0, the areas of track 6, track 3, and track 1 are shown, respectively. The area of track 1 shown in FIG. 2 (D>) will be explained below as an example. In this case, f1 to f
4 indicates that the frequencies of the pilot signals recorded on this track are fl, f2 . f3. It shows that it is f4. Therefore, this track 1 is set to the head switching pulse 1.
When A and B heads scan based on 000, f1f2
．． f3. In the order of f4, the regenerated pilot signal 100 is input to the balanced modulator 2 via the bandpass filter 1. At this time, the timing generator 11 operates as shown in FIGS.
) The 5ei1, 2 signals are output to the reference signal oscillator 3 at the timing indicated by ). That is, this Sea 1 , Se,
+22 high and low combination, reference signal oscillator 3
is fl, f2°f3. A reference signal having a frequency of f4 is sequentially generated and supplied to the balanced modulator 2. The combinations of 5ei1 and 5ei2 and the frequencies of the generated reference signals are as shown in the table below.

(Margins below) Here, let us consider the case where when the head switching pulse 1000 is at a high level, the head scans track 1, and the reproduced pilot signal f1 is obtained at the timing shown by A in Fig. 2 (D>); At this time, during the period when head A is operating the first half l of the playback area of track 1, the Se and j11 signals are at high level, and the 5ei2 signal is also at high level. A frequency f10 reference signal is supplied to the balanced modulator 2. Therefore, a difference frequency signal component 1300 for tracking control is taken out from the comparator 8. During this period, the timing generator 11 samples the sample-hold timing signal 500. The error signal @400 output to the hold circuit 12 and taken out from the switch 9 is sampled and held at the timing shown by A in FIG. 700.Next, during the period when head A is operating the rear solder of the playback area of track 1, the Set!1 signal is at low level and the 5ei2 signal is at high level, so the frequency is output from reference signal oscillator 3. f2
A reference signal is supplied to the balanced modulator 2, and a difference frequency component 1300 for recording speed determination is taken out from the comparator 8.

During this period, the timing generator 11 outputs the sample-and-hold timing signal 600 to the sample-and-hold circuit 13, as shown by A in FIG. The difference frequency signal component 1300 is sampled and held at the timing shown in A of FIG. When 1ooo is at a low level, the B head scans track 1, and at the timing shown in Fig. 2 (D>), the reproduction pilot signal = f 2 becomes 1.
q, the 5811 signal is low level in the first half of the playback area of track 1, and se! 2 signal becomes high level, a reference signal of frequency f2 is supplied from the reference signal oscillator 3 to the balanced modulator 2, and a difference frequency signal component 1300 for tracking control V is taken out from the comparator 8. Next, in the latter half m of the playback area of track track 1, Se
1'l signal is at a high level, Se and g2 signals are at a high level, a reference signal of frequency f1 is supplied from the reference signal oscillator 3 to the balanced modulator 2, and a difference frequency signal component 1300 for recording speed determination is extracted. . In the end, the reference signal oscillator 3 supplies the balanced modulator 2 with a reference signal having the same frequency as the reproduced pilot signal frequency in the first half l of the head reproduction area, and in the latter half m, the frequency of the reproduced pilot signal is fl.
.

f, ff, the frequency f1. f2. f22 3・
4 fl, T3. T4. T4. Supplying the T3 reference signal,
A tracking control difference frequency signal component 1300 is obtained from the first half of the reproduction area, and a difference frequency signal component 1300 for recording speed determination is obtained from the second half.

By the way, the tracking control described above is performed using the number hold timing signal Q500 at T3 shown in (G) in FIG.
The sample hold circuit 12 is opened only in the section and the error signal q400 is passed through, but in the other section (T1
-T3), a pre-hold state is entered. On the other hand, in the recording speed determination area, when the recording speed and the reproduction speed match and tracking control is being performed, a signal with a frequency of fH is always generated, and a signal with a frequency of 3fH is not generated. This signal with a frequency of fH13fH is compared by the comparator 8, and becomes a signal with a frequency of 1f[+-3fHl. This is sampled and held near the center of the recording speed discrimination area by the sample and hold circuit 13, and this length pull-hold value is used to shape the waveform. The waveform is shaped by the circuit 14.

Therefore, the waveform shaping circuit 14 always outputs a high level signal, as shown by (K) in FIG. FIG. 3 schematically shows the signals of frequencies fH and 3fH obtained at this time and their detected amplitudes. As can be seen from this figure, the speed discrimination area only needs to consider the attack time on the fil side and the recovery time on the 3fH side, and the sample hold timing for tracking is therefore longer than the conventional one. I can do it.

Next, if the recording speed and playback speed do not match,
Since the above state cannot be maintained, the levels of the signals of frequencies fH and 3fH both change. Therefore, the output of the waveform shaping circuit 14 repeats high and low levels. As a result, the speed discrimination logic circuit 15 knows that the recording speed and reproduction speed are different, and outputs a speed discrimination signal. At this time, the speed discrimination logic circuit 15 outputs a signal after the timing when the sample hold circuit 13 performs a long pull hold (T1-T2+T4 +T
5) The high level and low level of the signal 900 output from the waveform shaping circuit 14 are detected during any period of the period, and processing is performed to prevent erroneous detection.

According to this embodiment, in the first half l and the second half m of the playback area where the same pilot signal is recorded, base 1 (signal 20
By supplying different frequencies of 0 to the balanced modulator 2, a difference frequency signal component 1300 for tracking control is obtained from the first half 1, and a difference frequency signal component 1300 for recording speed determination is obtained from the second half m. Therefore, for the recording speed determination area, it is only necessary to consider the attack time on the FLL side and the recovery time on the 3F[1 side, and the period for sampling and holding the tracking control signal can be lengthened by this amount. Tracking control and recording speed discrimination can be performed satisfactorily by reducing the adverse influence of the recording speed discrimination signal on the tracking control signal.

[Effects of the Invention] As described above, according to the magnetic recording and reproducing apparatus of the present invention,
The recording speed can be determined based on the pilot signal reproduced from a minute section by transmitting a tracking control signal from the first half of the playback area where pilot signals of the same frequency are recorded, and a signal for recording speed determination from the second half. This has the effect of smoothly performing tracking control.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the magnetic recording/reproducing device of the present invention, FIG. 2 is a chart showing the operation timing of FIG. 1, and FIG. A schematic diagram showing an example of a waveform obtained by detecting the amplitude of these signals, FIG. 4 is a diagram showing an example of a minute section track that is magnetically recorded and reproduced, and FIG. 5 is a diagram showing a tracking control signal from the first half of the minute section, FIG. 6 is a waveform diagram of each signal when speed determination signals are extracted from the latter half. 2... Balanced modulator 3... Reference signal oscillator 8
...Comparator 9...Switch 11...
Timing generators 12, 13...Sample and hold circuit 15...Speed discrimination logic circuit Agent Patent attorney Nori Chika Ken Shu Uji Hiroshi (Cj CJ LJ LtJ LL Ul --11
Figure 4 Figure 5

Claims (1)

[Claims] A magnetic recording and reproducing device that records a pilot signal whose frequency changes cyclically together with an information signal, and performs tracking control and recording speed determination using a difference frequency signal obtained by multiplying the reproduced pilot signal by a reference signal during reproduction. In this method, the frequency of the reference signal to be multiplied by the obtained reproduced pilot signal is made different between the period when the magnetic head is scanning the first half of the reproduction area where the same pilot signal is recorded and the period when the magnetic head is scanning the second half. a reference signal supply means for supplying a reference signal in the first half of the reproduction area; a means for sampling and holding a difference frequency signal obtained by multiplying a reproduction pilot signal and a reference signal supplied in the first half of the reproduction area as a tracking control signal; A magnetic recording/reproducing device characterized by comprising means for using a difference frequency signal obtained by multiplying a pilot signal and a reference signal supplied in the latter half of the reproduction area as a recording speed determination signal, and sample-holding the signal. Device.