JPH046655A - Tracking control method for rotary head type digital audio tape recorder - Google Patents

Abstract

PURPOSE:To reduce the hold time of a tracking error signal obtained from a reproduction signal and to make the tracking servo stable by using a prescribed tracking error signal for a prescribed time in an optional timing. CONSTITUTION:A 1st gate circuit 13 selects only three sampling pulses a, b, c, in first two traces at which a reproduction output is sufficiently obtained among consecutive four traces to apply tracking control and selects a gate signal of a 2nd gate circuit 16 to be at a high level as shown in figure (d) for a prescribed tie after the production of the 3rd sampling pulse (c). Simultaneously a moving contact 15a of a switch circuit 15 is turned to the position (b) thereby applying a center voltage of the ATF servo servo system generated by a constant voltage generating section 14 to a capstan motor drive circuit for a prescribed time tx till the 1st sampling pulse (d) in the consecutive four traces is generated. Thus, the tracking error signal is held for a long period to suppress the apparent gain thereby implementing effective tracking control.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a tracking control method for an R-DAT.
In particular, it relates to a tracking control method during double scanning.

(b) Conventional technology Conventionally, in R-DAT, in addition to the standard mode, the tape speed
There is an optional mode that records at half the cylinder rotation speed as in the standard mode.

In order to playback tapes recorded in this option mode, a double scan method is used in which the tape speed is set to half that of the standard mode and the cylinder rotation speed is the same as in the standard mode, taking into consideration the playback frequency band. Regarding this double-scan tracking method, please refer to Japanese Patent Application Laid-Open No. 137456 (G11B15/46).
7) and will be explained below.

FIG. 3 shows a block diagram of the tracking control circuit of R-DAT, in which (1) is a playback input terminal, (2
) is a regeneration amplifier, (3) is a low-pass filter for pilot signal extraction, (4) is an envelope detection circuit, (5)
(6) is a first sample and hold circuit that samples the input signal using the sampling pulse SPI; (6) is a subtracter that calculates the level difference between the hold signal of the first sample and hold circuit (5) and the output signal of the detection circuit (4); ,(
7) is a second sampling and holding circuit that samples the input signal using the sampling pulse SP2, and its output becomes a tracking error signal and is sent to the output terminal (8).
output from the capstan motor drive circuit (not shown). (9) is a reproduction/equalizer circuit for waveform equalization, (1
0) is a comparator for digital conversion that binarizes the output signal,
(11) is a control circuit that outputs sampling pulses, (
13) is the first and second
This is a first gate circuit that selectively supplies sampling pulses to the sampling hold-low paths (5) and (7).

A tracking method using the trunking control circuit having the above configuration will be explained with reference to FIGS. 4(a) to 4(C). Fig. 4(a) shows the henodic switching signal, Fig. 4(a)
b) is a diagram showing the timing of the sampling pulses output by the control circuit (11). During normal playback, all sampling pulses are used for tracking control, but during double scan, the timing shown in Fig. 4(C) is shown. As shown in , the gate circuit (13) supplies only the sampling pulses (a), (b), and the sampling pulses (C) of the first trace to the second sample and hold circuit (7). Tracking control is performed by generating a tracking error signal at the timing of sampling pulses (a), (b), and (c).

(C) Problems to be Solved by the Invention However, according to the double-scan tracking control method described in the prior art, the tracking error signal obtained at the timing of the sampling pulse of the second trace of the four consecutive traces is , more than 2 traces are held, so the influence of the error signal is very large. For example, in trunking control of a tape with a high unerased signal level during override recording, the gain of the tracking servo increases and an offset state occurs.
This causes instability of the tracking servo.

(d) Means for Solving the Problems The present invention is intended to solve the above-mentioned problems. In a rotary head type digital audio tape recorder that forms a tracking area and performs tracking control using a control signal recorded in the tracking area during playback, the tape speed and cylinder rotation speed are half of the standard recording/playback mode. When playing a digitally recorded tape in the optional recording/playback mode with reduced speed, the tape speed is half that of the standard recording/playback mode, and only the cylinder rotation speed is the same as in the standard recording/playback mode. Tracking control of R-DAT that performs tracking control by switching at arbitrary timing between a tracking error signal obtained from a reproduced signal that can obtain a sufficient reproduced output and a constant tra-kink error signal. Suggest a method.

(E) Effect According to the above means, the holding time of the tracking error signal obtained from the reproduced signal can be shortened by using a constant track/l kink error signal at an arbitrary timing for a certain period of time.

(F) Example A system for realizing the trunking control method during double scan of the present invention will be explained below with reference to FIG. Therefore, the explanation will be omitted. ( ] 4) is a constant voltage generator that supplies a constant voltage to the capstan motor drive circuit (not shown) as a tracking error signal.
It is composed of A and R11.

(15) is the tracking error signal generated by the second sample hold circuit (7) or the constant voltage generator (1
A switch circuit (16) selectively supplies the tracking error signal from the switch circuit (16) to a capstan motor drive circuit (not shown);
5a) is a second gate circuit that generates a gate signal for switching.

The tracking operation during double scanning in the tracking control circuit having the above configuration will be described below with reference to FIG. First, among the four consecutive traces, in the first two traces where a sufficient reproduction output can be obtained, the first gate circuit (13) generates three sampling pulses (a) (as shown in FIG. 2(C)). Tracking control is performed by selecting only (b) and (c), and after a certain period of time (for example, the time for 1/2 rotation of the rotating cylinder) after the generation of the third sampling pulse (C), the image shown in Fig. 2 ( At the same time as the gate signal of the second gate circuit (16) is switched to No. 1 as shown in d), the actuator (15a) of the switch circuit (15) is switched to the side (b) as shown in the figure. , constant voltage generator (
14) Supply the center voltage of the ATF servo system generated in step 14) to the capstan motor drive circuit (not shown) for a fixed time t8 until the time when the first sampling pulse (d) of the next four consecutive traces is generated. . After that, as mentioned above, the gate signal of the second gate circuit (6) becomes low, the actuator (1, 5a) of the switch circuit (15) is switched to the (a) side, and the second sample and hold circuit (7) is switched to the (a) side. )
Tracking control is performed using the tracking error signal generated by the tracking error signal.

Incidentally, Fig. 2(a) is a diagram showing the reproduced signal, and Fig. 2(b) is a diagram showing the reproduced signal.
FIG. 2(e) is a diagram showing the H/E switching signal, and FIG. 2(e) is a diagram showing the tracking error signal.

(G) Effects of the Invention According to the method of the present invention, sufficient reproduction output can be obtained in trunking control during double scanning! By holding the tracking error signal using the third sampling pulse in the L2 trace for a long time, it is possible to reduce the off-cent trunk and suppress the apparent gain, so tracking due to unerased components due to override can be suppressed. Effective tracking control can be performed against instability.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the tracking control circuit of R-DAT for realizing the tracking control blade of the present invention, and Fig. 2 (a) to (e) are for explaining the tracking control method of the present invention. 3 is a block diagram showing a conventional R-DAT tracking control circuit, and FIGS. 4(a) to (C) show various signals for explaining the conventional tracking control method. It is a diagram. (13)...first gate circuit, (14)...constant voltage generator, (15)...switch circuit, (16)...second
gate circuit.

Claims (1)

[Claims] (1) A tracking area is formed at the beginning and end of each trace of each track of the tape that is helically scanned by a rotating head, and tracking control is performed using the control signal recorded in the tracking area during playback. In rotary head type digital audio tape recorders, when playing digitally recorded tapes in an optional recording/playback mode in which the tape speed and cylinder rotation speed are reduced to half of the standard recording/playback mode, the tape speed is reduced to the standard. The tracking error signal obtained from the playback signal that can obtain sufficient playback output by performing playback with half the recording/playback mode of the standard recording/playback mode and with only the cylinder rotation speed the same as the standard recording/playback mode, and the tracking error signal obtained from a constant tracking error signal. A tracking control method for a rotary head type digital audio tape recorder in which tracking control is performed by switching between and at arbitrary timing.