JPH0248995Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention is made to obtain good tracking by separately recording signals for tracking, video signals, audio signals, and color signals. This invention relates to a tracking device.

(Prior Art) As a means for applying tracking servo, a conventional magnetic recording/reproducing apparatus uses a rotating recording head to record a luminance signal, a low frequency conversion color signal, and a pilot signal for tracking in a superimposed manner. In terms of spectrum, the recorded signal is as shown in FIG. Third
In the figure, _fA is an audio signal, _fC is a low frequency conversion color signal, and ₁ to ₄ are tracking pilot signals.

For example, four different frequencies ₁ , ₂ , ₃ , and ₄ are prepared as pilot signals, and each of them is sequentially selected and recorded for each track.

Tracking servo is performed by reproducing the pilot signal recorded in this manner. That is, when the servo is disconnected and the reproducing head enters an adjacent track, two different pilot signals are reproduced, so a beat signal is generated between them and the original pilot signal. The amount of track deviation is detected by the magnitude of this beat signal, the direction of track deviation is detected by the beat frequency of the beat signal,
It controls the running speed of the magnetic tape and the rotation speed of the rotary head.

(Problem to be solved by the invention) By the way, in the above method, in order to record the pilot signal in a superimposed manner with the video signal, audio signal, low-frequency conversion color signal, etc. in the same recording head, many beats and cross-modulation signals are generated. There was a problem that something like this occurred.

(Means for Solving the Problems) The tracking device of the present invention includes a rotating drum having a recording/reproducing head and a plurality of erasing heads, and when the range erased by one erasing head is one track, In a magnetic recording/reproducing device in which erasing frequencies differ for each adjacent track, a beat frequency detecting means detects the beat frequency of two erasing frequencies generated between adjacent tracks due to track deviation, and detection by the beat frequency detecting means The apparatus is equipped with a running speed control means for controlling the running speed of the magnetic tape based on the beat frequency, and a rotational speed control means for controlling the rotational speed of the recording/reproducing head and the erasing head based on the beat frequency.

(Embodiment) FIG. 1 is a schematic block diagram showing an example of a tracking device according to the present invention.

A pulse signal having a constant period outputted from the oscillation circuit 1 is divided into four different division ratios (1/1) by the frequency divider 2.
T ₁ to 1/T ₂ ), and selector switch 3
are respectively supplied to each input terminal. On the other hand, the drum reference signal (PG pulse) S ₁ inputted from the input terminal 17 is differentiated by the differentiating circuit 5 and inputted to the flip-flop circuit 6 . A switching pulse is output from the flip-flop circuit 6 to the changeover switch 3. The signal output from the changeover switch 3 is supplied to the erasing heads a and b of the rotary drum 7 via the changeover switch 4. Moreover, the changeover switch 4 is
The switching is performed by a reproduction/recording switching signal inputted from the input terminal 21.

A head polarity switching circuit 9 switches the polarity of the recording/reproducing heads A and B for each track. The timing of this switching is controlled by the drum reference signal (PG pulse) _S1 input from the input terminal 19 to the polarity reversing circuit 8.

Reference numeral 10 denotes a video/audio recording/reproducing circuit for reproducing the output of the recording/reproducing head A or B, which is switched by a recording/reproducing switching signal inputted from an input terminal 22.

The tracking frequency component output from the video/audio recording/reproducing circuit 10 is amplified by a tracking frequency amplification circuit 11 and then amplified by a beat frequency detection circuit 12.
The signal is detected and supplied to the drum servo circuit 13 and capstan servo circuit 15.

A drum reference signal (PG pulse) S ₁ is input to the drum servo circuit 13 from an input terminal 17, and a drum reference signal (PG pulse) S ₁ is input from an input terminal 18 during reproduction. Further, a capstan reference signal S ₂ is input to the capstan servo circuit 15 from an input terminal 20 .

FIG. 2 shows the recording pattern of the magnetic tape.

Signals ₁ to ₄ are recorded by erasing heads a and b, and other helical recorded signals are recorded by recording/reproducing heads A and B. As shown in Figure 2,
One type of erasing frequency is recorded on one track, and the erasure frequency is switched and recorded sequentially for each track in the order of ₁ , ₂ , ₃ , ₄ , ₁ , _{2, .} . . . In FIG. 2, the arrow x indicates the direction in which the head travels, and the arrow y indicates the direction in which the magnetic tape travels.

In the tracking device configured as described above, when recording, first, the erasing frequency of the erasing head a is set to ₁ to erase the data, and the recording/playback head A records video, audio, color signals, etc., and superimposes it on the previous erasing frequency _{of 1} . . Next, erasing is performed by setting the erasing frequency of erasing head B to ₂ , and the recording/reproducing head B records video, audio, color signals, etc., and superimposes them on the previous erasing frequency ₂ . Once again, erase with the erase frequency of erase head a set to ₃ , perform superimposition recording in the same way on recording/playback head A, then erase with the erase frequency of erase head b set to ₄ , and repeat the same operation on record/playback head B. Record overlapping. Repeat the above operations to record.

During reproduction, an erasing frequency is frequency-selected and extracted from the reproduction signal of the recording/reproducing head A or B, and is amplified by the tracking frequency amplification circuit 11. When the recording/reproducing head A or B travels on a track other than the determined one, it also reproduces the different erasing frequencies of the other tracks. The beat frequency generated for this purpose is detected by a beat frequency detection circuit 12 and supplied to a drum servo circuit 13 and a capstan servo circuit 15.

Here, ₁ , ₂ and ₃ due to track deviation
Let the beat frequency of _{4 be a} , and the beat frequencies of ₂ and ₃ and ₁ and ₄ be _b , and _a ≠ _b . By detecting the amount of track deviation and the direction of the track deviation based on the magnitude of the beat frequency _a or _b , it is possible to determine whether the running speed of the magnetic tape or the rotational speed of the head is leading or slowing.

The drum servo circuit 13 has the beat frequency
_a or _b and the drum reference signal S ₁ input from the input terminal 18. These signals control the speed of the drum motor 14, that is, record/record.
The rotational speeds of the reproducing heads A, B and the erasing heads a, b are controlled.

Further, the capstan servo circuit 15 is supplied with the beat frequency _a or _b and the capstan reference signal S ₂ input from the input terminal 20 . These signals cause the capstan motor 16 to
In other words, the running speed of the magnetic tape is controlled.

(Effects of the invention) Since the tracking device of the invention performs tracking control using the beat frequency of the cancellation frequency, no beat or cross-modulation occurs, and the cancellation frequency also serves as an cancellation signal for tracking. Therefore, there is no need to separately record a pilot signal for tracking.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a tracking device according to the present invention, FIG. 2 is a diagram showing a recording pattern of a magnetic tape, and FIG. 3 is a diagram showing a recording signal frequency spectrum in an 8 mm video format. 7... Rotating drum, 11... Tracking frequency amplification circuit, 12... Beat frequency detection circuit, 1
3...Drum servo circuit, 15...Capstan servo circuit, A, B...Record/playback head, a,
b... Erasing head.

Claims (1)

[Claims for Utility Model Registration] A rotary drum having a recording/reproducing head and a plurality of erasing heads, and when the range erased by one erasing head is one track, the erasing frequency is different for each adjacent track. In a magnetic recording and reproducing apparatus, a beat frequency detection means detects the beat frequency of two erasing frequencies generated between adjacent tracks due to track deviation, and a beat frequency detected by the beat frequency detection means is used to detect the beat frequency of a magnetic tape. A tracking device comprising: a traveling speed control means for controlling the traveling speed; and a rotational speed control means for controlling the rotational speed of a recording/reproducing head and an erasing head based on a beat frequency.