JP2656545B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing method, and particularly to a phase compensation method suitable for high-frequency short-wavelength recording.

[Prior art] Conventionally, in the tape head recording / reproducing process, as described in NHK Technical Research Showa 44 “Basic Research on Design of Magnetic Recording Devices”, the phase shows a linear change, and the phase shift occurs. In addition, no phase compensation circuit was provided for the recording / reproducing process.

[Problems to be solved by the invention]

The above prior art does not consider the phase characteristics of the tape head system, and has a problem that it cannot cope with a phase shift of the tape head system.

In particular, when recording is performed at a short recording wavelength of 1 μm or less, and the thickness of the magnetic layer of the recording medium is approximately equal to the recording wavelength.
If it is larger than 1/4, the magnetization pattern remaining on the magnetic tape after recording / reproducing shows not only a component in the running direction of the magnetic tape, so-called longitudinal direction, but also a so-called vertical component in the thickness direction. There is a phase difference of 90 ° between the longitudinal direction and the vertical component, and the appearance of this vertical component changes with the recording wavelength. If the recording signal is a recording / reproducing system in which signals of various recording wavelengths must be recorded / reproduced, such as an NRZ signal, in other words, if a wideband recording / reproducing system is required, the above phase shift is reproduced. Has a significant effect on the signal,
In the case of digital recording, it has been found that the error rate is reduced by one or two digits.

An object of the present invention is to compensate for the phase shift occurring in the tape head system as described above.

[Means for solving the problem]

The above object can be achieved by adding a phase compensation circuit for compensating for a phase shift occurring in a tape head system.

Another object is to provide a phase compensation circuit for compensating for a phase shift occurring in a circuit other than the tape head system and a phase compensating circuit added for the phase shift occurring in the tape head system. It can also be achieved by compensating with a phase compensation circuit.

[Action]

The phase shift occurring in the tape-head system causes a phase shift in addition to a recording wavelength and a vertical component in addition to a longitudinal component. In terms of the group delay time, one example has characteristics as shown in FIG. As described above, by compensating for the phase shift occurring in the tape head system, decoding with few errors can be performed from the reproduced signal.

〔Example〕

Embodiment 1 FIG. 1 shows a schematic configuration of an apparatus according to an embodiment of the present invention, which comprises a tape head system 1, a preamplifier 2, an amplitude compensation circuit 3, and phase compensation circuits 4 and 5. The minute reproduction signal obtained by the tape head system 1 is amplified by the preamplifier 2, the amplitude frequency characteristic of the tape head system 1 is compensated by the amplitude compensating circuit 3, and the tape head system 1 and the amplitude compensating circuit 3 are compensated by the phase compensating circuits 4 and 5. Each phase shift that occurs is compensated.

The signal written on the tape 1a is read by the head 1b, amplified by the preamplifier 2, and subjected to amplitude compensation by the amplitude compensation circuit 3. FIG. 3 shows frequency characteristics required for amplitude compensation. The output signal of the amplitude compensation circuit 3 has a phase shift occurring in the tape head system 1 and a phase shift of the amplitude compensation circuit 3. FIGS. 4 (a) and 4 (b) show this phase shift as a group delay time. The group delay characteristics of the tape head system 1 and the amplitude compensating circuit 3 are compensated by the phase compensating circuits 4 and 5, respectively, and flattened.

 FIG. 5 shows the group delay characteristics after compensation.

According to the present invention, since the phase shift of the tape head system is also compensated, the equalizing capability of the equalizing circuit is improved.

Embodiment 2 A second embodiment will be described with reference to FIG.

The apparatus according to the present embodiment includes a tape head system 1, a preamplifier 2, an amplitude compensating circuit 3, and a phase compensating circuit 6.

The signal recorded on the tape is read out by the tape head system 1 using the head. The read signal is amplified by the preamplifier 2. The amplified signal fluctuates in amplitude and phase more than when recorded due to the characteristics of the tape head system 1. Only the amplitude component of this variation is compensated by the amplitude compensation circuit 3. The amplitude-compensated reproduced signal has a phase shift generated in the tape head system 1 and a phase fluctuation generated in the amplitude circuit. In this embodiment, the phase compensation generated by the tape head system 1 and the phase compensation circuit 3 was compensated by the phase compensation circuit 6 together. As a form of the phase compensation circuit, it is simple and effective to connect the emitter side and the collector side of the transistor shown in FIG.

〔The invention's effect〕

According to the present invention, since the phase shift of the tape head system is also compensated, the effect of improving the performance of the equalizing circuit can be obtained.

[Brief description of the drawings]

1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a group delay frequency characteristic diagram of a tape head system, FIG. 3 is a frequency characteristic diagram of an amplitude compensating circuit 3, and FIG. FIG. 5 is a group delay characteristic diagram after phase compensation, FIG. 6 is a block diagram of the second embodiment, and FIG. 7 is a circuit diagram showing an example of a phase compensation circuit actually used. FIG. Reference numeral 1 denotes a tape head system, 2 denotes a preamplifier, 3 denotes an amplitude compensating circuit, 4 denotes a phase compensating circuit 1 and 5, a phase compensating circuit 2 and 6, a phase compensating circuit.

Claims (1)

(57) [Claims] 1. A magnetic tape in which a digital signal is recorded on a magnetic layer at a recording wavelength of 1 μm or less, and a thickness of the magnetic layer is larger than about / 4 of the recording wavelength, and a magnetic tape is recorded on the magnetic tape. A magnetic head for reading the digital signal, an amplitude compensating means for compensating the amplitude frequency characteristic of the output signal from the magnetic head, and a phase compensating means for making the group delay frequency characteristic of the output signal of the amplitude compensating element substantially flat. A magnetic recording / reproducing apparatus for reproducing the digitally recorded signal.