JP2810484B2 - Tracking control method for rotary head digital audio tape recorder - Google Patents

Description

The present invention relates to an R-DAT tracking control method,
In particular, it relates to a tracking control method at the time of double scanning.

(B) Conventional technology Conventionally, in R-DAT, the tape speed,
There is an optional mode in which recording is performed by setting the cylinder rotation speed to half of the standard mode.

The tapes recorded in this optional mode are played back in double scan mode, in which the tape speed is set to half that of the standard mode in consideration of the playback frequency band, and the cylinder rotation speed is made the same as in the standard mode. The tracking method of the double scan method is disclosed in Japanese Patent Application Laid-Open No. 1-137456 (G11B15 / 467), and will be described below.

FIG. 3 is a block diagram of a tracking control circuit of the R-DAT, wherein (1) is a reproduction input terminal,
(2) is a reproduction amplifier, (3) is a low-pass filter for pilot signal extraction, (4) is an envelope detection circuit,
(5) is a first sample-and-hold circuit for sampling an input signal by the sampling pulse SP1, and (6) calculates a level difference between a hold signal of the first sample-and-hold circuit (5) and an output signal of the detection circuit (4). (7) is a second sampling and holding circuit for sampling the input signal by the sampling pulse SP2,
The output is output as a tracking error signal from an output terminal (8) to a capstan motor drive circuit (not shown). (9) is a reproduction equalizer circuit for waveform equalization,
(10) a comparator for digital conversion for binarizing an output signal, (11) a control circuit for outputting a sampling pulse,
(13) is the first and second playback modes for playback.
The first gate circuit selectively supplies a sampling pulse to the sampling and holding circuits (5) and (7).

A tracking method using the tracking control circuit having the above configuration will be described with reference to FIGS. 4 (a) to 4 (c). FIG. 4 (a) shows a head switching signal, and FIG. 4 (b) shows the timing of sampling pulses output from the control circuit (11). In normal reproduction, tracking is performed using all sampling pulses. The control is performed, but at the time of double scan, as shown in FIG. 4C, the gate circuit (13) applies the sampling pulses (a) and (b) of the first trace to only the sampling pulse (c) of the second trace. The signal is supplied to a two-sample hold circuit (7) and its three sampling pulses (a) and (b)
The tracking control is performed by generating a tracking error signal at the timing (c).

(C) Problems to be Solved by the Invention However, according to the tracking control method of the double scan method described in the conventional technique, the tracking error signal obtained at the timing of the sampling pulse of the second trace out of four continuous traces is Since two or more traces are held, the effect of the error signal is very large. For example, in the tracking control of a tape having a high remaining erase signal level during overwrite recording, the gain of the tracking servo increases, an offset state occurs, and the tracking servo is performed. Cause instability factors.

(D) Means for Solving the Problems The present invention has been made to solve the above problems, and has a tracking area at each of a trace start end and a trace end of each track of a tape to be helically scanned by a rotary head. In a rotary head digital audio tape recorder that performs tracking control using a control signal recorded in its tracking area during playback, the tape speed and cylinder rotation speed are reduced to half that of the standard recording / playback mode. When playing back a digitally recorded tape in the optional recording / playback mode, the tape speed is set to half that of the standard recording / playback mode, and only the cylinder rotation speed is the same as the standard recording / playback mode, and playback is performed. A tracking error signal obtained from a playback signal that provides a sufficient playback output and a fixed track An R-DAT tracking control method is proposed in which tracking control is performed by switching between a king error signal and an arbitrary timing.

(E) Operation According to the above means, the hold time of the tracking error signal obtained from the reproduction signal can be shortened by using the constant tracking error signal at an arbitrary timing for a certain time.

(F) Embodiment A system for realizing the tracking control method at the time of double scanning according to the present invention will be described below with reference to FIG. ,
The description is omitted. (14) is a constant-voltage generator for supplying a constant voltage to the capstan motor drive circuit (not shown) as a tracking error signal, the power supply VCC and the resistor R _A, R _B
It is composed of

(15) is a tracking error signal generated by the second sample and hold circuit (7) or the constant voltage generator (1).
4) A switch circuit for selectively supplying the tracking error signal from the capstan motor drive circuit (not shown) to the capstan motor drive circuit (not shown). (16) is an actuator (15a) of the switch circuit (15).
Is a second gate circuit that generates a gate signal for switching between .gamma.

The tracking operation at the time of double scanning in the tracking control circuit having the above configuration will be described below with reference to FIG. First, in the first two traces in which a sufficient reproduction output is obtained among four consecutive traces, the first gate circuit (13) performs three sampling pulses (a) (a) (FIG. 2C). b) Tracking control is performed by selecting only (c), and a certain time (for example, a rotating cylinder) after the third sampling pulse (c) is generated.
After 1/2 rotation), the gate signal of the second gate circuit (16) is switched to high as shown in FIG. 2 (d), and at the same time the actuator (15a) of the switch circuit (15) is turned on. As shown in (b), the center voltage of the ATF servo system generated by the constant voltage generator (14) is applied to the capstan motor drive circuit (not shown) at the beginning of the next four traces. supplying a certain period of time t _x until time of occurrence of the sampling pulse (d). Thereafter, as described above, the gate signal of the second gate circuit (16) becomes low, and the operator (15a) of the switch circuit (15) is switched to the (a) side, and
Tracking control is performed by a tracking error signal generated by the sample hold circuit (7).

2 (a) is a diagram showing a reproduction signal, FIG. 2 (b) is a diagram showing a head switching signal, and FIG. 2 (e) is a diagram showing a tracking error signal.

(G) According to the method of the present invention, in the tracking control at the time of double scanning, the tracking error signal using the third sampling pulse in the two traces for sufficiently obtaining the reproduction output is held for a long time. Since the offset track can be reduced and the apparent gain can be suppressed, effective tracking control can be performed for tracking instability due to the unerased component due to overwriting.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an R-DAT tracking control circuit for realizing the tracking control method of the present invention;
2A to 2E show various signals for explaining the tracking control method of the present invention, and FIG.
FIG. 4 is a block diagram showing a DAT tracking control circuit,
FIGS. 1A to 1C are diagrams showing various signals for explaining a conventional tracking control method. (13) ... first gate circuit, (14) ... constant voltage generator,
(15) ... switch circuit, (16) ... second gate circuit.

Claims (1)

(57) [Claims] A tracking area is formed at each of a trace start end and a trace end of each track of a tape to be helically scanned by a rotary head, and tracking control is performed using a control signal recorded in the tracking area during reproduction. A rotary head type digital audio tape recorder, comprising: a constant voltage section for generating a predetermined voltage; and switching means for switching between a tracking error signal obtained from a reproduction signal and an output signal of the constant voltage section. , A tape recorded in the recording / reproduction mode with the tape speed and cylinder rotation speed suppressed to half of the standard recording / reproduction mode, and the tape rotation at half the standard recording / reproduction mode and the cylinder rotation of the standard recording / reproduction mode When reproducing by number, the above-mentioned A tracking control method for a rotary head type digital audio tape recorder, wherein the tracking error signal is switched to the output voltage of the constant voltage section by switching means, and tracking control is performed by the output signal of the switching means.