JPS5898861A - magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an automatic recording time mode in helical scan V'l''H in which a pilot signal is multiplexed and recorded on a recording track as a tracking signal for the recording track instead of a control signal. Regarding the discrimination method.

Conventional home VTRs use 2 or 5 types of recording when recording.
It is common practice to record at the same tape speed (recording and playback times differ for the same cassette; hereinafter referred to as recording time mode), and the recording time mode is automatically determined during playback, and the recording time mode is automatically determined and the tape speed and playback time at the time of recording are changed. It has been attempted to perform playback at the same tape speed. Conventionally, control signals recorded on control tracks have been used for this purpose. A control signal? used. As a method to eliminate various drawbacks associated with tracking of recording tracks, a method has been used in which a pilot signal for tracking is multiplexed together with an information signal on a recording track, and this pilot signal is used to perform tracking of a recording trunk. ing. (hereinafter referred to as the pilot method)
In the case of this pilot method, since there is no control signal, automatic determination of the recording time mode using a control signal, which has been done conventionally, cannot be applied, and a new method is required.

The present invention relates to automatic determination of recording time mode in a pilot method.

The present invention automatically determines the recording time mode by changing the spatial arrangement of pilot signals to be multiplexed on a recording track depending on the recording time mode.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIGS. 1 and 2 show an embodiment in which a 24-fold recording time mode is set in a four-frequency pilot system in a two-head helical scan IITH using a so-called azimuth head.

In the four-frequency pilot system, pilot signals of four frequencies are multiplexed with the 11 broadcast signal and sequentially recorded on each recording track. In an X-ray VTR, these frequencies are set to the lower frequency side of the frequency band of the low frequency converted color signal, and in one example, approximately fl=6.5fH, fz-
7, 5fH, fa-q, 5fn, f<=1o, 5fH
selected. (fH horizontal travel i, linear frequency) In Fig. 1, 1 is a magnetic tape, 2 is a recording track recorded by a rotating magnetic head A (hereinafter referred to as head A), and 3 is a rotating magnetic head B (hereinafter referred to as head A). This is a recording track recorded by a head (referred to as head B).

FIG. 1 shows the case written in the recording time mode ■, and the input signals are fl, fz, f4. Superimposition recording can be completed on each track in the order of fa. On the other hand, Fig. 2 shows the recording time mode ■, in which case the pilot signals are fI, fa,
They are recorded in the order of f= and fz. From Figures 1 and 2, fl,
fa is head A, f2. f3 is recorded by head B. Therefore, in order to change the spatial arrangement of the pilot signals from FIG. 1 to FIG. 2 during recording 1, it is sufficient to reverse the order of fz and 13 recorded by head B, and the change can be easily made.

During reproduction, heads A and B reproduce not only the main track but also pilot signals of adjacent tracks as crosstalk components. For example, in the first cycle, when head A is running uphill on the fl track, the adjacent pilot signal f3. j2
are also played at the same time.

In order to obtain a tracking error signal, the pilot signal f3. from this adjacent track is used. The reproduction level difference of f2 is detected and used as a tracking error signal. For example, in Fig. 1, when scanning the f1 track, is the level of fz or the level of fa? The subtracted value is used as a tracking error signal, and if it is positive, fl) The head is off to the right with respect to the rack, so the head is shifted to the left.
If it is negative, shift it to the right and use servo control to
Set the tracking error to o. However, as is clear from a comparison between FIG. 1 and the second intermittent signal, the pilot signal frequencies of the adjacent trucks in FIG. 1 and FIG. This is because the spatial arrangement of the pilot signals in FIG. 1 and FIG. 2 are symmetrical to each other in a left-hand, archaic chain. From this result, the polarity of the tracking error signal in FIG. 1 and FIG. 2 is reversed.

Therefore, in order to correctly reproduce a recording tape recorded in the pattern shown in FIG. 2, it is necessary to add a circuit for inverting the polarity of the tracking error signal compared to that in FIG. 1, but this can be realized with a simple circuit.

In the four-frequency pilot system, the pilot frequency of the adjacent trunk reproduced during reproduction is frequency-converted and extracted as a difference frequency between the pilot frequency of the main track. Now tentatively set this reference main pilot frequency as fI.
shall be. (Of course, this also applies to other frequencies.) Generally, four frequencies are circulated around this main pilot frequency, so the above means considering the case when the main pilot frequency is jl. do.

In this case, the amount of tracking error 2 with respect to the amount of track deviation and the repopulation level of the pilot signal of frequency f= are shown in FIGS. As is clear from FIG. 3, the polarity of the tracking error signal is reversed in recording time modes E and II, and it is possible to use this to determine the mode. An example of this will be explained below with reference to FIG.

From the head reproduction signals from heads A and B, only the pilot signal is extracted by the low-pass filter 5. The output of the low-pass filter 5 is a band-pass filter 6 with a center frequency f1.
and is supplied to the tracking error generation circuit 7. The tracking error generating circuit is well known and will not be described in detail here. Normally, when the recording tape speed and the reproduction tape speed are different, the amount of track deviation increases linearly. The output of the bandpass filter B is input to an envelope detection circuit 12, and the output of the envelope detection circuit 12 and the output of the tracking error generation circuit 7 are input to waveform shaping circuits 8 and 9, respectively. The outputs of waveform shaping circuits 9 and 8 are shown in FIG. 3, d, t, and f, respectively. As is clear from FIGS. 3d, e, and f, when the output level from the waveform shaping circuit 8 is high level, the output of the waveform shaping circuit 9 changes from low level to high level in recording time mode E. When the signal changes from a high level to a low level, it is possible to detect the percentage of f conversion. The output of the waveform shaping circuit 9 is not supplied to the gate circuit shown on the right, and the output of the gate circuit 10 shows that the output of the waveform shaping circuit 8 is at a high level and the output of the waveform shaping circuit 9 is changed from a low level to a high level. In other words, a pulse is generated in the recording time mode E, and a pulse is generated in the output of the gate circuit 11 in the recording time mode II.These pulses are supplied to the set and reset terminals of the flip-flop 13, respectively. , when the recording time mode is set to E, the output of the flip 70 knob 16 is set to high level, and when set to H, set to low level. In this case, the polarity of the tracking signal input to the servo circuit is reversed.

Note that the output of the waveform shaping circuit 8 is Lp gated to the j1 pulse by the gate 14, and is output only when the fx multiplied signal is used as the main pilot signal. This f1 pulse is a pulse generated while fl is used as the frequency conversion reference frequency of the tracking error generation circuit, and is generated by a known technique. For example, even when the temporal change in track deviation is small by 7, as in the case of slow playback, there is always a moment when the f1', - rack center ya-,71 head crosses, so the detection of the recording time mode is t'T. It is M@.

An embodiment of the present invention has been described above with respect to seven examples of the four-frequency pilot system, but the main point of the present invention is to change the spatial arrangement of pilot signals depending on the recording time mode.
In particular, when there are two types of modes, the pilot signals for these modes should be arranged in a chain symmetrical manner, and the method is not limited to the four-frequency pilot system.

A case in which the present invention is applied to an example of a single frequency pilot system will be described below. Parts 5 and 6 are single-frequency pilots (
An example in which No. S is recorded in the horizontal flyback section of a television signal is shown. The figures show a part of the recording pattern. 1. FIG. 5 is an example of recording time mode I, and FIG. 6 is an example of recording time mode II.

Tracks B1 to B4 where A1 to A4 are recorded with A head
is the track recorded with the B head. In the example of FIG. 5.6, one frequency pilot signal is recorded every four horizontal scanning line periods (hereinafter referred to as H). In the figure, the shaded area indicates the pilot signal recording area. In the same way as described for the example of the four-frequency pilot system, in this example as well, the pilot signals of the main track and the adjacent track are simultaneously reproduced by the head. As is clear from Figure 5, the pilot signals of both adjacent trunks are recorded at different positions on the left and right adjacent tracks, so it is not possible to distinguish the reproduced pilot signals from the adjacent tracks that are reproduced from the left and right. , correct tracking can be achieved by performing servo control to make these levels equal. The example shown in FIG. 5 assumes the case of the azimuth recording method, and is designed to prevent stable scanning of erroneous recording tracks with different azimuths.

FIG. 7 shows the envelope waveform of the reproduced pilot signal when the tracks recorded in FIGS. 5 and 6 are scanned. The pilot signal of the track currently being scanned is the largest, and the pilot signals of adjacent tracks are smaller and are reproduced at different reproduction timings. As shown in FIG. 7, using the maximum reproduction pilot signal detection timing as a reference, the levels of the pilot signals reproduced after IH, 2H, and OH are respectively p+, p2, . If p3, then tracking error signal E.If head A is reproducing, then (EA) Eh=p+-pz+p3. If head B is playing (set as Es) EB-7)2
-ps-p+ -E*. Comparing Figures 5 and 6, both figures are completely symmetrical, and when looking left and right from the trunk currently being scanned, the left and right sides of Figures 5 and 6 are completely reversed. Therefore, the tracking error signal E has the same absolute value in FIGS. 5 and 6, and its polarity is reversed.

FIG. 8 shows the amount of tracking error with respect to the amount of track deviation and the reproduction level (reproduction envelope waveform) of the information signal. (Since the azimuth method is used, information signals of adjacent tracks are not reproduced over time, as in the previous embodiment.) Assuming that the amount of track deviation increases in proportion to D, the horizontal axis in FIG. 8 can also be regarded as time. Therefore, when the waveform of FIG. 8 is shaped with reference to the center level, it becomes as shown in FIG. 9 αl/)l'. This figure is shown in Figure 6d.
t and f. Therefore, it is recommended to use the envelope waveform of the reproduced information signal in place of the output of the envelope detection circuit 12, and to calculate the recording time using a circuit completely similar to the circuit shown in FIG. The mode can be automatically determined. In this case, it is obvious that the gate 14 shown in FIG. 4 is unnecessary.

Next, an embodiment of the present invention in another example of the single frequency pilot system will be explained with reference to FIGS. 10 to 12. FIG. 10 shows an example of the alignment time mode (2), and FIG. 11 shows an example of the recording time mode (2). - Recording frequency pilot signals in the horizontal retrace section is the same as in the cases described in FIGS. 5 and 6, but in this example, pilot signals having a phase difference of 180° are used. In Figures 10 and 11, the recorded pilot signal is 0.
1800 phases are recorded differently at the location where it is written and the location where it is written as n. In this example, by using the I'J and 2ji delay lines, inputting the reproduced pilot coefficient, and adding or subtracting the output and input, the pilot signal of the main track and the pilot signal of the adjacent track can be calculated. are distinguished. Further, among the pilot signals reproduced from the adjacent tracks, the left and right adjacent pilot signals are distinguished by determining the difference in the pilot signal recording position using the main trunk pilot signal position as a reference. In this case as well, the patterns in Fig. 10 and the patterns in Fig. 11 are chain symmetrical, just like the ones described above, and the left and right tracks of the main track are the 10th track. The diagram and FIG. 11 are reversed.

In FIG. 10, the pilot signal is recorded at the same position as the main trunk in the right adjacent track of the track (A+A2, A3) in which the polarity of the pilot signal is not reversed to 2H, and it is deviated in the left adjacent track. For tracks with reversed polarity, this is reversed left and right.

However, in FIG. 11, this relationship is completely reversed, and the left adjacent track of the track (fJh, B2.Bs) whose polarity is not reversed is at the same position as the main track.

Therefore, the polarity of the obtained tracking error signal is also reversed. FIG. 12 shows the tracking error signal (E) and the reproduced signal envelope waveform in this case. FIG. 12 is almost the same as FIG. 8, and it is obvious that the recording time mode can be automatically determined by the same means as described in connection with FIG.

In order to produce the pattern shown in FIG. 11 from the recording pattern shown in FIG. 10, the positions of the by-12-lot signals recorded by head B may be switched between track 81 and track B2. (Replace B3 with B4. Replace them sequentially from now on.) This is possible with a simple circuit-equipped blade during recording.

In this case, the recording head will be as shown in the lower part of FIG. 11, but this is not essential.

, 41i: According to the invention, when a pilot signal is used for tracking, it is possible to reliably discriminate the recording time mode at any playback tape speed, and the discrimination circuit involved is also very simple. stomach. Therefore cheap! It is possible to create a magnetic recording/reproducing device 17 having a plurality of types of recording time modes, which can automatically and reliably determine the recording time mode.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the pilot signal recording pattern of one embodiment of the present invention, FIG. 3 is a diagram showing the amount of tracking error associated with the embodiment of FIGS. 1 and 2, and FIG. Figure 2 is a circuit diagram of the recording time mode discrimination circuit of the embodiment, Figures 5 and 6 are diagrams showing recording patterns of other embodiments of the present invention, and Figure 7 is a reproduction pilot of the embodiment of Figures 5 and 6. Figure 8 is a diagram showing the amount of tracking error in the embodiment shown in Figures 5 and 6. Figure 9 is a diagram showing the waveform after shaping of the waveform in Figure 8. Figures 1Q and 11 are diagrams showing signal waveforms. FIG. 12 is a diagram showing still another embodiment of the present invention. FIG. 12 is a diagram showing the amount of tracking error in the example of FIG. 11; 1: Magnetic tape, 2.6° recording track, 6: Band pass filter, 7: Trunking error generation circuit, 13: Free knob. Representative Patent Attorney Susuki 1) Li voice 15 years old 1 figure wise? Mao 3 Figure iIF Fu・su 7--] Thio 4 Diagram 5 Diagram r Otsu Kutsuo Photo Diagram reference fimi〉7゛o 8 Diagram Akebono (c) B1 Δy f 13211A3 year old 9 Figure 1) - la・ノ7hi0so÷+IO diagram? II Figure

Claims (1)

[Claims] In a helical scan VTR that has a plurality of rotating magnetic heads with different azimuths, records at different tape speeds during recording, and records a pilot signal for tracking along with an information signal during recording, it is possible to adjust the tape speed during recording. A magnetic recording/reproducing device characterized in that the spatial arrangement of pilot signals is changed and recorded accordingly.