JPH0719335B2 - Floppy disk drive data playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a data reproducing device for a floppy disk device using a perpendicular recording system.

(Prior Art) Conventionally, in a floppy disk device, an in-plane (longitudinal) recording method or a perpendicular recording method is used as a method for magnetically recording data on a recording medium (disk). It is known that the vertical recording method is particularly suitable for a high density recording mode.

In a floppy disk device, a bit detection circuit that detects a peak of a reproduction signal from the head and outputs a pulse signal that inverts at this peak point when the recording data is reproduced after being recorded on a recording medium by the head. It is provided. The bit detection circuit includes a differentiating circuit that differentiates the reproduction signal from the head and a zero-cross detection circuit (comparator). The differentiating circuit differentiates the reproduction signal from the head as shown in FIG. 5 (a) and outputs a differential waveform as shown in FIG. 5 (b). Here, the reproduction signal shown in FIG. 9A is a signal waveform read by the head from the recording medium recorded by the in-plane recording method. Each peak of the reproduction signal corresponds to the zero cross point of the differential waveform. The zero-cross detection circuit outputs a pulse signal that inverts so as to rise or fall at the zero-cross point of the differential waveform. This pulse signal is processed by the pulse shaping circuit and converted into a read pulse.

By the way, the reproduced signal waveform read from the recording medium recorded by the perpendicular recording method is an asymmetrical waveform whose phase advances as compared with the case of the in-plane recording method (see FIG. 2). Therefore, when reproducing data, the bit detection circuit in the in-plane recording system as described above cannot obtain the differential waveform corresponding to the peak of the reproduced signal waveform corresponding to the in-plane recording system, resulting in It is not possible to obtain an accurate read pulse.

(Problems to be Solved by the Invention) In the perpendicular recording method, if a bit detection circuit in the longitudinal recording method is used when reproducing data, it is not possible to obtain an accurate read pulse corresponding to the longitudinal recording method. For this reason, conventionally, in order to obtain compatibility with the in-plane recording method, there is a method of using a phase equalizing circuit or a twice differentiating circuit in a data reproducing apparatus of the perpendicular recording method. However, the phase equalizer circuit has a complicated structure and is difficult to adjust, and the twice differentiator circuit has a drawback that the noise is increased and the SN ratio is lowered because the high frequency band is emphasized.

It is an object of the present invention to provide a data reproducing device for a floppy disk device capable of obtaining an accurate read pulse based on the peak of a reproduced signal with a simple structure in a perpendicular recording system.

[Configuration of the Invention] (Means and Action for Solving the Problem) The present invention relates to a low-pass filter circuit for removing an unnecessary frequency component of a reproduction signal read from a head in a perpendicular recording system, and this low-pass filter circuit. To detect the peak of the LCR series resonance circuit and the playback signal output from the LCR series resonance circuit for executing the correction processing of the phase and amplitude of the playback signal output from the, and to generate the pulse signal based on this peak It is a data reproducing device equipped with the bit detection circuit of.

With such a configuration, it becomes possible to shift the peak of the reproduction signal to the peak position corresponding to the in-plane recording method and reproduce the accurate read pulse based on this peak.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the arrangement of a data reproducing apparatus used in a vertical recording type floppy disk apparatus according to the embodiment. The apparatus of the embodiment includes a head 11 for reading data from a recording medium 10 recorded by a vertical recording method, a preamplifier 12 for amplifying a reproduction signal from the head 11, a low pass filter (LPF) 13, an LCR series resonance circuit. 14 and a bit detection circuit 15. The LPF 13 removes noise, which is an unnecessary high frequency component, from the reproduction signal output from the preamplifier 12. In this case, the cutoff frequency of the LPF 13 is usually about twice the highest continuous frequency (2f). LC
The R series resonance circuit 14 corrects the phase and amplitude of the reproduction signal output from the LPF 13, and corrects the peak to the peak position corresponding to the in-plane recording method. The bit detection circuit 15 has a differentiation circuit and a zero-cross detection circuit, and the LCR series resonance circuit 14
The peak of the reproduction signal from is detected and a pulse signal based on this peak is generated.

Next, the operation of the embodiment will be described. In the floppy disk device, the head 11 executes a data read operation from a target track of the recording medium 10 when in the data reproduction mode. Data is magnetically recorded on the recording medium 10 by the perpendicular recording method. The head 11 converts the magnetic flux from the recording medium 10 into a voltage and outputs it to the preamplifier 12. The LPF 13 removes unnecessary high frequency component noise from the reproduction signal from the preamplifier 12 and outputs a reproduction signal A having a waveform as shown in FIG. That is, in the data reproduction mode of the vertical recording method, the reproduction waveform becomes an asymmetric waveform in which the phase advances as compared with the in-plane recording method. When such a reproduced signal is differentiated by the differentiating circuit of the bit detection circuit 15, it is not possible to obtain a differential waveform that zero-crosses at the peak point of the reproduced signal. Specifically, the waveform of the reproduction signal shown in FIG. 3 (a) (however, the perpendicular squareness ratio 0.8 which is the magnetic characteristic of the recording medium 10,
When the medium material is barium / ferrite), the differential waveform is as shown in FIG.

Therefore, in the present invention, the LCR series resonance circuit 14 allows the LPF13
The phase of the reproduction signal A output from the is corrected and the reproduction signal B having the waveform as shown in FIG. 2 is generated. In this case, the main band of the waveform of the reproduction signal A in the vertical recording method is LC
The phase correction is performed so that it is near the resonance point of the R series resonance circuit 14. The resonance point of the LCR series resonance circuit 14 normally corresponds to the frequency of the shortest continuous magnetization reversal signal.
Further, by setting the resistance R of the LCR series resonance circuit 14 to a predetermined value, the so-called damping effect (damping factor “(R / 2) √C / L” is set to 1.5, for example) is used to obtain an amplitude characteristic. Can have relatively close to flat characteristics. Further, since the amplitude can be attenuated in the high range above the resonance point of the LCR series resonance circuit 14, the high range noise can be suppressed.

The reproduction signal B output from the LCR series resonance circuit 14 is differentiated by the differentiation circuit of the bit detection circuit 15. The differentiated waveform is a waveform such that the zero-cross point is at the bit position, as shown in FIG. 3 (c). The bit detection circuit 15
The zero-cross detection circuit outputs a pulse signal which is inverted so as to rise or fall at the zero-cross point of the differential waveform. That is, as shown in FIG. 2, the bit detection circuit 15 outputs a pulse signal according to the peak of the reproduction signal B. This pulse signal is shaped by a pulse shaping circuit (not shown) and converted into a read pulse which is reproduction data.

Note that FIG. 4 (a) is a waveform of a reproduction signal from a recording medium (for example, vertical squareness ratio 0.95) having a large phase rotation (advance of phase) in the vertical recording method, and FIG. Similar to (b), it is a differential waveform when the output is directly differentiated from the LPF 13. 4C is a differential waveform obtained by differentiating the reproduction signal of FIG. 4A by the LCR series resonance circuit 14 after phase and amplitude correction (damping factor is 0.9). Even in this case, as in the case described above, the differential waveform of FIG. 4 (c) is a waveform such that the zero-cross point is at the bit position.

[Effect of the Invention] As described in detail above, according to the present invention, in a perpendicular recording type floppy disk device, a simple configuration and large noise are used without using a phase equalization circuit or a second differentiation circuit. Without this, it is possible to correct the phase and amplitude of the reproduced signal by the vertical recording method. Therefore, as a result, an accurate read pulse based on the peak of the reproduction signal can be obtained with a simple structure, and a reliable data reproduction operation can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a data reproducing apparatus according to an embodiment of the present invention, FIGS. 2 to 4 are waveform charts for explaining the operation of the embodiment, and FIG. 5 is a conventional surface. FIG. 6 is a waveform diagram for explaining a data reproducing operation in the inner recording method. 10 ... Recording medium, 11 ... Head, 13 ... Low pass filter, 14 ... LCR series resonance circuit, 15 ... Bit detection circuit.

Claims (1)

[Claims] 1. A head for reading data from a recording medium magnetically recorded by a perpendicular recording system, a low-pass filter circuit for removing unnecessary frequency components of a reproduced signal read from the head, and a low-pass filter circuit. An LCR series resonance circuit for executing the correction processing of the phase and amplitude of the reproduction signal output from the filter circuit, and the peak of the reproduction signal output from this LCR series resonance circuit is detected, and the pulse signal based on this peak is detected. And a bit detection circuit for generating the data. A data reproducing device of a floppy disk device.