JPS63234439A - Tracking control signal generator - Google Patents

Abstract

PURPOSE:To stably and surely reproduce a signal at double speed by comparing reproduced envelope levels in plural prescribed positions of a recording track and using the level difference as tracking information. CONSTITUTION:A reproduced signal (a) has the envelope detected by an envelope detecting circuit 11 and is supplied to a sample-and-hold circuit 12 and the inverted input terminal of a level comparator 13. A signal (c+) which has the level held by a sampling pulse (i) is outputted from the sample-and-hold circuit 12 to the non-inverted input terminal of a level comparator 13. Subtraction is performed in the level comparator 13, and the output is supplied to a sample-and-hold circuit 14. A square wave (e) is generated since a sampling pulse (k) is supplied to the sample-and-hold circuit 14 from a sampling pulse generating circuit 19, and this square wave (e) is supplied to a capstan motor driving control circuit of the following stage as the tracking control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a tracking controlled VLA signal generator, and particularly to a rotary head type digital audio tape recorder (hereinafter referred to as rR- D.A.
The present invention relates to a tracking W signal generating device suitable for being connected to a recording/reproducing device such as a “T device”.

(Prior Art) In the following description, the tracking control signal generating device of the present invention will be described as being installed in an R-DAT device. Conventionally, the R-DA D5iiff has a pair of rotating heads with different azimuth angles mounted on the side surface of the rotating drum, and these rotating heads record a recording pattern as shown in Fig. 6 on a magnetic tape T (hereinafter referred to as 8.15 ll1m/se
While traveling at a speed of c, signals are recorded while forming a track with a track width of approximately 13.6 μm obliquely (approximately 6° 23') to the traveling direction. Furthermore, during playback, each rotary head reliably traces the home track (track with the same azimuth angle) using a unique tracking method. That is, when playing back at normal speed, the ATF (Auto Tr.
The pilot signal J'+ (approximately 13
11 tHz>, first and second synchronization signals/2. H3
Tracking information such as (respectively 522k1%, 784kllz) is reproduced, tracking is performed to equalize the level of pilot signal leakage of four adjacent tracks, and key 1! The rotation speed υ of the Pustan motor is controlled.

In the Kakaru R-DAT device, the rotating head (H^, H6 in Figure 2) is installed on the surface of the rotating drum at a point symmetrical position with respect to the rotation axis, and the magnetic tape (hereinafter simply referred to as "tape") is ) is attached to the surface of the rotating drum by about 1/4 of a turn. Therefore, during one revolution of the rotary drum, recording (or reproduction) and rest are alternately performed for approximately the same amount of time. In addition, taking into account the tape running speed, the inclination angle of the track with respect to the running direction, and the width of the rotating head H^ and HB, the tape F should have no gaps between the tracks, and a slight gap (approximately 1/3 of the head width) in the middle. Since the track width is narrower than the width of the rotating head, the rotating head (A, HB has an azimuth angle (±20°)).
is provided, and high frequency components are greatly attenuated, so there is almost no problem such as interference between adjacent tracks of the PCM A-D'A signal during reproduction.

[Problems to be solved by the present invention]

When performing triple speed rewind playback (hereinafter also referred to as rREW playback) with R-DATVtff having such a configuration, the AT
When F is used, audio digital data recorded in areas other than both ends of the track is attenuated, making it difficult to perform good skip playback. This current system will be explained with reference to FIG. 2 and subsequent figures. Figure 2 shows the rotating head HA I H during 3x REW playback.
The locus of a, Fig. 3 (6) is the rotational head torque lA at that time.
The reproduced waveform by lH3, and (B) in the same figure is a rotational phase synchronization signal waveform. If you perform skip playback with ATF tracking as described above, as shown in Figure 2,
There was a problem in that the data in the center of the envelope was attenuated. The following can be considered as ways to bring out the problem. That is, the rotating head HA is rotated while feeding or rewinding the tape T.

When performing double-speed playback, rewind playback, or high-speed search using t-1e, as shown by traces A and B in Fig. 2,
The rotary heads HA and Ha cross a plurality of recording tracks diagonally, and each track is reproduced only for a short time when it comes into contact with a head of the same azimuth angle.
As shown in , in the case of triple speed, to each rotating head H,
The reproduced waveform shown in Figure 3 (in order for 6 to trace adjacent tracks with the same azimuth angle by crossing one track with a different azimuth angle by 40 degrees from the same track with the same azimuth angle) is It is thought that there will be a large attenuation.

[Failure to solve the problem]

The tracking control signal generating device of the present invention uses a rotary head to reproduce signals on a magnetic tape on which information signals are recorded while tracks are formed in a helical shape using a plurality of rotary heads having different azimuth angles. In the tracking control signal generation device of the playback device, an envelope detection circuit that detects an envelope of the playback signal;
A first and second sampling pulse generation circuit that generates first and second sampling pulses that are shifted by different predetermined times from the rising and falling edges of the rotational phase synchronization signal for the rotating head, and an envelope detection circuit. A first sample bold circuit samples and holds the envelope of the reproduced signal output from the first sampling pulse, and outputs a signal with a level obtained by subtracting the envelope level of the reproduced signal from the output level of the first sample hold circuit. and a second level comparator that samples and holds the output signal of the level comparator with a second sampling pulse.
The above-mentioned drawbacks have been solved by configuring the sample-and-hold circuit.

That is, instead of using the ATF to control the drive of the main 11 bustan motor that drives the tape, a signal obtained by processing a part of the information signal is used to control each rotary head torque lA, H.
This problem is solved by shifting B forward or backward one track at a time.

(Example) In short, the tracking & lJ trust generating device of the present invention is capable of recording and recording signals when using a rotary head to reproduce signals on a magnetic tape on which information signals are recorded while tracks are formed in a helical shape. The playback envelope levels at a plurality of predetermined positions on a track are compared and the level difference between them is used as tracking information.The tracking control signal generator of the present invention is described below with reference to FIG. 1 and FIG. 3 onwards. I will explain while doing so. FIG. 1 shows an embodiment of the tracking control signal generator 10 of the present invention, and In+ in the figure is an input terminal to which a reproduced signal is supplied;
2 is an input terminal to which a rotational phase synchronization signal is supplied, 11 is an envelope detection circuit for detecting the envelope of the reproduced signal, 12.14 is a number hold circuit, 13 is a level comparator, 15 is an edge detection circuit, 16. 17 is a delay circuit, 18 and 19 are sampling pulse generation circuits, and OUT is an output terminal for tracking control signal.

Next, the functions and operations of each component will be explained with reference to FIG. 3 and subsequent figures. Rotational phase synchronization signal I for switching the rotary head coming from input terminal In 2 (Fig. 3)
(see B)) is supplied to the edge detection circuit 15, where the rising and falling edges of the signal are detected. That is, the edge detection circuit 15 generates a pulse Q as shown in FIG. 3(C) and supplies it to the next stage delay circuits 16 and 17. Delay circuit 1
6 and 17 have different delay times, respectively (
D), (Outputs a rectangular wave j as shown in Fl.

Each rectangular wave.

j is detected by the sampling pulse generating circuits 18 and 19, respectively, and as a result, the falling edge of the pulse j is detected by the sampling pulse generating circuits 18 and 19, respectively.

(Sampling pulses L and k are output as shown in Q.The timing of generation of sampling pulses L and K is as shown in FIG.
This is immediately after TF area α1 and immediately before α2. ATF area α1. The reason for excluding α2 is that the signal level is not stable in the ATF area.

On the other hand, the playback signal a from the input terminal In+ repeats the indicated waveform forever while the tape running is controlled by the AT (see Figure 3), but the servo (travel speed control) by the ATF is When removed, the head gradually turns to zero 1]8,)-1
8 and the home track (track with the same azimuth angle) on the tape shifts, and the peak and dip positions change as shown in Figure 5. (This is shown in the figure; in reality, this change is gradual.) The reproduced signal a is subjected to half-wave rectification in the envelope detection circuit 11 as shown in FIG. The sample and hold circuit 12 outputs the signal C+ whose level is held by the sampling pulse (see (C) in the figure) to the non-inverting input terminal of the level comparator 13. Since the regenerated signal @b (C- signal in the same figure (C)) from the envelope detection circuit 11 is supplied as is to the inverting input terminal of the Same figure ([
) is output and supplied to the sample and hold circuit 14. Since this sample hold circuit 14 is supplied with the sampling pulse k from the sampling pulse generation circuit 19, a signal whose level is held at the timing of the pulse input, that is, a rectangular wave e shown in FIG. 0 is generated. This is supplied as a tracking control signal (a?I difference signal) to a capstan motor drive control circuit (not shown) at the next stage. Therefore, for example, if the error signal level is positive, it is determined that there is a "phase lag" and the motor's four-speed rotation is controlled to speed up in proportion to the thickness of that level, and conversely, if the level is negative, it is determined that there is a "phase delay". is determined to be a "phase advance" and the speed is slowed down. As a result, the waveform of the reproduced signal a gradually becomes as shown on the right side of Figure 5, and at that point the error signal The level becomes approximately O. After that, as shown in (1) in Fig. 3, medium pressure waveforms occur continuously.In this state, the internal rotating heads H^, H8 is played back with a one-track shift, and as a result, the amount of attenuation of the desired audio signal level decreases, resulting in 3x speed playback or 3x R speed playback.
This means that EW regeneration can be performed stably and favorably.

In the above description, the tracking control signal generating device of the present invention has been described as being installed in an R-DAT device, but the present invention is not limited to this, and signals such as tracking control can be traced by a plurality of magnetic heads having different azimuth angles. The playback device can be used in any device as long as it can perform double-speed playback.

(Effect) Tracking control signal generation S of the present invention! ! Since the device is configured as described above, if this device is installed in, for example, four R-DATVs that can perform double-speed playback at around 3x speed, it is possible to obtain a high-quality triple-speed playback signal with little attenuation, allowing stable and reliable double-speed playback. Practical 1: It has an excellent effect of being able to realize the following.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the tracking υJlill signal generating device of the present invention, FIG. 2 is a diagram showing the trace state in a conventional R-DAT device that does not have a tracking control signal generating device, and FIG. ) are timing charts for explaining the VJ operation of the tracking control signal generating device, respectively, and (B) is a timing chart for explaining the VJ operation of the tracking control signal generating device. Second
A timing chart for explaining the timing of sampling pulse generation of f! FIG. 6 is a diagram illustrating the recording pattern of the signal recorded by the R-DAT device. 10...Tracking control signal generator, 11...
Envelope detection circuit, 12.14... Sample hold circuit, 13... Level comparator, 15... Edge detection circuit, 16.17... Delay circuit, 18.19...
・Sampling pulse generation circuit, In+, ln2...
Input terminal, Out...output terminal. Patent applicant: Japan Victor Co., Ltd. 74～゛ Representative: Kawamizu Kuni Dave Katsuyoshi

Claims (1)

[Claims] In a tracking control signal generator of a device that uses a rotary head to reproduce signals on a magnetic tape on which information signals are recorded while forming helical tracks using a plurality of rotary heads having different azimuth angles, an envelope detection circuit that detects the envelope of the signal, and a second sampling pulse that generates first and second sampling pulses that are shifted by different predetermined times from the rising and falling edges of the rotational phase synchronization signal for the rotary head. 1. A second sampling pulse generation circuit and a first sampling pulse that samples and holds the envelope of the reproduced signal output from the envelope detection circuit using the first sampling pulse.
a sample hold circuit, and a level comparator that outputs a signal having a level obtained by subtracting the envelope level of the reproduced signal from the output level of the first sample hold circuit;
A tracking control signal generating device comprising: a second sample and hold circuit that samples and holds the output signal of the level comparator using the second sampling pulse.