JPS6126959A - Magnetic tape reproducer - Google Patents

Abstract

PURPOSE:To attain an accurate tracking action by driving with control a capstan motor so as to set the output difference between both tracks at zero since the output voltage of a sample-and-hold circuit is proportional to the projected amounts of both tracks. CONSTITUTION:The output of an RF amplifier 13 is applied to a tracking detection circuit 11 and separated by a filter 14. This separated output is rectified by a rectifier 15 and applied to sample-and-hold circuits 16 and 17 respectively. The outputs of both circuits 16 and 17 applied to a differential amplifier 18. Thus the difference of both outputs is obtained and a tracking error signal TE is outputted. This output TE is turned into the voltage which shows an offset amount, i.e., a tracking error amount sent from a track center of a head. A capstan motor 5 is driven with control so as to set the voltage TE at zero. Thus an accurate tracking action is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital audio tape recorder (hereinafter referred to as DA).
The present invention relates to a magnetic recording/reproducing device that can be used for the following applications: (abbreviated as T), etc.

Conventional Structure and Problems There is a video tape recorder (hereinafter abbreviated as VTR) as a conventional device that forms helical tracks on a magnetic tape. Regarding tape tracking, a VTR is equipped with a control head exclusively for tracking. During recording, the control head records a reference signal on the magnetic tape, and during playback, the control head plays back the reference signal on the magnetic tape, and the control head performs tracking. The usual method was to ensure tracking by controlling the capstor/motor so that the phase of the reproduced signal was synchronized with the reference frequency for the purpose.

This method has a problem in that the control head installation tends to be distorted due to accuracy, temperature changes, and changes over time, and there is also large variation among manufacturers.

To solve the above problem, we omitted the control head and replaced it with 8? Like an IJVTR, during recording, a pilot signal is recorded as tracking information in the form of FM modulation over the entire video track, and during playback, two pilot signals leaking from the trunks on both sides adjacent to the playback track and a pilot signal from the own trunk are recorded. An ATF method has been proposed in which tracking is performed by controlling a capstan motor so that the amplitudes of two difference frequency signals detected from the oscilloscope are equal. Particularly in DAT and the like, recording information over a wide band is required, so a method has been proposed in which tracking information is recorded separately from audio digital data in a plurality of small portions on a track.

With this ATF method, the erasing head used in VTRs is eliminated, and in order to re-record on the magnetic tape that has already been recorded, the recording head is used to record in the same way as the first time.
If the erasing characteristics are not sufficient, ATF error detection occurs and tracking cannot be performed normally.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic tape reproducing apparatus that does not require an erasing head and can reproduce data with normal tracking no matter how many times it is rerecorded.

Structure of the Invention The magnetic tape playback device of the present invention records information by forming helical-shaped tracks on a magnetic tape using a rotating blade, and outputs a tracking signal, a synchronization signal, and an interblock signal at a predetermined position on each track. A device for reproducing a magnetic tape recorded with a tracking information area in which signals are recorded, comprising a synchronization signal detection circuit, a tracking detection circuit for detecting tracking information from the tracking signal, and an inter-block signal or tracking signal detection circuit. It consists of a limiting circuit that stops the operation of the synchronization signal detection circuit when detected, and a drive means that runs the magnetic tape using the output signal of the tracking detection circuit.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the main parts for explaining the tracking method (ATF) of the magnetic recording and reproducing apparatus of the present invention, in which 1 is a cylinder that holds the heads 1a and 1b and rotates them at high speed; A motor for rotating the cylinder, 3 a position detector for detecting the rotational phase of the cylinder 1 and the rotational positions of the heads 1a and 1b, and 4 a phase control loop between the motor 2 and the position detector 3. The rotation of the motor 2, that is, the cylinder 1, is controlled in phase synchronization with the reference frequency f8 by the constituent phase control circuit.

6 is a capstan motor for running the tape 12; 6a is a frequency generator that outputs a signal with a frequency proportional to the number of revolutions of the capstan motor 5; 6b is a capstan motor that uses the output of the frequency generator 6 & A speed control circuit for controlling the motor 6 at a substantially constant speed; 9 is an adder; 10 is a drive circuit for the capstan motor 6; (The capstan motor 5 and the drive circuit 1o serve as the drive means.)
7 is a limiting circuit that detects an inter-block signal from the outputs of the heads 1a and 1b; 8 is a synchronizing signal detection circuit that outputs a pulse when there is no output from the limiting circuit 7 and a synchronizing signal is detected from the outputs of the heads 1a and 1b; 9 is a synchronization signal detection circuit 8
This is a tracking detection circuit that samples and holds tracking signals from the outputs of the heads 1a and 1b at an appropriate timing when the head 1b outputs a pulse. The rotation of the capstan motor 5 is controlled via the drive circuit 10 by the sum of the output of the speed control circuit 6b and the output of the tracking detection circuit 1.1, and the tape 12 is rotated to each recorded track.
Traveling is controlled so that a and 1b are on track.

The operation will be explained in more detail.

FIG. 2 shows an example of the tracking information area on the tape 12. In FIG. 2(a), F indicates the tracking information area on TR, and ■ indicates the area where other information is recorded. There is.

FIG. 2(b) shows a specific example below the tracking information area, in which the same signal is recorded in the portion where the same notching has been applied. In Fig. 2(b), fp is a tracking signal, f8
is a synchronization signal, fb is an interblock signal, and track T
Moving over R, DoH moves in the direction of arrow Ha and reads the signal.

FIG. 3 shows the limiting circuit 7. A specific example of the synchronization signal detection circuit 8 and the tracking detection circuit 11 is shown. FIG. 4 shows an example of the tracking information area when the tape is re-recorded once, and FIG. It shows the operating waveforms of each circuit in FIG. 3 when the head H moves in the tracking information area.

The operation will be explained with reference to FIGS. 3, 4, and 6.

In FIG. 3, an RF (high frequency) amplifier 13 amplifies the outputs of the heads 1a and ib, a limiting circuit 7, a synchronizing signal detecting circuit 8. The signal is applied to the tracking detection circuit 11. The limiting circuit 7 separates the inter-block signal fb (see FIG. 4) from this signal using a filter 24, rectifies it using a rectifier 25, and compares it with the DC voltage v1 using a comparator 26. Therefore, the fourth
When the head H moves along the track shown in the figure, the output of the comparator 26 is at a logic level 0 only when there is an inter-block signal fb, and at a logic level 1 otherwise, as shown in FIG. 5(b).
become that way.

Here, W in FIG. 4 is where the inter-block signal fb is written, but it shows a part where the synchronizing signal fs has already been recorded in the previous recording and has not been completely erased by the inter-block signal fb.

The output of the RF amplifier 13 is still applied to the synchronization signal detection circuit 8, the synchronization signal fs is separated by the filter 19, rectified by the rectifier 2o, and applied to the comparator 21.

In the comparator 21, the output of the rectifier 2o and the DC voltage v2
When the output of the limiting circuit 7 is at logic level 1 in the AND circuit 22, the output of the AND circuit 22 becomes equal to the output of the comparator 21. The output of the AND circuit 22 becomes the output signal of the synchronizing signal detection circuit 8, and at the same time becomes another output signal via the monostable multivibrator 23.

In FIG. 6, (C) is the output of the filter 19,
(7) is the playback output of the moving own track of the head H, (A) and (1) are the crosstalk of the adjacent track, and (V is the composite output section of the crosstalk of the remaining track W and the adjacent track in Fig. 4). The output of the rectified waveform of FIG. 5(C) and comparison by the comparator 21 is as shown in FIG. 6(d).One input of the AND circuit 22 has the output shown in FIG. 6(b).
Since the signal shown in FIG. 6(d) is input to the other side, the output of the AND circuit 22 becomes as shown in FIG. 6(e). The output of the AND circuit 22 is further applied to a monostable multivibrator 23, which outputs a pulse as shown in FIG. 5(g).

The output of the RF amplifier 13 is further sent to the tracking detection circuit 1.
1, separated by a filter 14, rectified by a rectifier 16, and applied to sample and hold circuits 16 and 17. The sample pulses of the sample and hold circuits 16 and 17 are the output signals of the synchronization signal detection circuit 8. The output of the sample and hold circuits 16 and 17 is a differential amplifier 18 with a gain of 1.
The difference is calculated and a tracking error signal TE is output.

The operation of the tracking detection circuit will be explained with reference to FIG.

In FIG. 6) is the output signal of the filter 14,
(3) is the cocoon talk of the adjacent track, and (a) is the tracking signal of the own track. This is rectifier 15
The current is rectified as shown in Figure 5(i). The signal shown in FIG. 6(i) is input to the sample and hold circuits 16 and 17, but the sampling of the sample and hold circuit 16 is as shown in FIG.
The sampling of sample hold 17 is performed at the leading edge of the pulse shown in e) (timing shown in Fig. 5 (f)), and the sampling of sample hold 17 is carried out at the pulse shown in Fig. 6 (cr). A DC voltage proportional to the crosstalk voltage from each adjacent track to the head H is held.

Crosstalk from adjacent tracks is proportional to the extent to which the head H protrudes to the adjacent track, so the output voltages of the sample and hold circuits 16 and 17 are proportional to the amount of protrusion of the head H to the adjacent track on the left and the adjacent track on the right, respectively. It will be proportional to. The differential amplifier 18 outputs the difference between the outputs of the sample and hold circuits 16 and 17, and its output TE becomes a voltage indicating the amount of offset of the head H from the trunk center, that is, the amount of tracking error.

In order to make the king error voltage TE zero,
By controlling the drive of the capstan motor 5 shown in FIG. 1, accurate tracking can be performed.

As described above, in the present invention, even if the sync signal fIil remains undisappeared as shown in FIG. detection and avoid false positives.

Effects of the Invention As described above, the magnetic tape playback device of the present invention has V
Even without an erasing head like the TR, the recorded information can be successfully tracked and reproduced even if it is rerecorded with a rotating head any number of times, and it has great effects on cost reduction and miniaturization, so it has great utility value. is high.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts for explaining a tracking method of a magnetic tape playback device according to an embodiment of the present invention;
2(a) and 2(b) are diagrams showing the recording patterns on the magnetic tape according to the above embodiment, FIG. 3 is a block diagram showing the detailed configuration of the main part, and FIG. 4 is a diagram showing other patterns in the above embodiment. FIG. 5 is an operational waveform diagram of the circuit shown in the block diagram shown in FIG. 3. 1a, 1b...Head, 12...Magnetic tape, F...Tracking information area, f...Tracking signal, fs...Synchronization signal, fb
...Inter-block signal, 8...Synchronization signal detection circuit, 11...Tracking detection circuit, 7-...
Limiting circuit, 6,1o...driving means. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 4 Figure 5] Cabinet ■ /AJ -! Shoulder Go]

Claims (1)

[Claims] A rotating head that records information by forming helical tracks on a magnetic tape using a rotating head, and a tracking information area provided at a predetermined position of each track,
In this tracking information area, a tracking signal for detecting on-track information of the reproducing rotary head, a synchronization signal for detection synchronization, and an inter-block signal for the portion where there is no tracking signal or synchronization signal are recorded on the magnetic tape. a synchronization signal detection circuit that detects the synchronization signal; a tracking detection circuit that detects the tracking signal based on the output of the synchronization signal detection circuit and outputs tracking information; 1. A magnetic tape playback device comprising: a limiting circuit for stopping the operation of the detection circuit; and a drive means for driving the magnetic tape using the output of the tracking detection circuit.