JPH02223004A - Magnetic data reader - Google Patents

Abstract

PURPOSE:To eliminate a reading error caused by a saddle, to improve noise resistance and to execute exact data reading by detecting a peak voltage by a boundary voltage detector, reproducing a clock by data themselves, obtaining synchronization and executing peak detection. CONSTITUTION:The read voltage from a magnetic head 10 is inputted through a low-pass filter 12 to a plus threshold comparator 30-1, which outputs a signal as the boundary voltage detector when the voltage is more than a plus boundary voltage, and a minus threshold comparator 30-2 which outputs a signal when the voltage is less than a minus boundary voltage. The signals from the comparators 30-1 and 30-2 are inputted to a D-type flip-flop and a clock reproducing device 32 and synchronized by a clock signal from the clock reproducing device 32. After that, pulse shaping is executed in a monostable multivibrator 36 as a pulse shaping device and the signals are outputted through a NOR circuit 38. Thus, the read voltage of the magnetic head is wholly digitally processed and there is no problem of the saddle. Then, the influence of the noise is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic data reading device, and particularly to a magnetic data reading device suitable for accurately reading data.

[Prior Art] Magnetic disks such as hard disks and floppy disks are widely used as auxiliary memory in computers and word processors as large-capacity, rewritable media.
Data is stored on the disk as magnetization changes of residual magnetization, and the magnetic head converts the magnetization changes into voltage changes and reads the data.

FIG. 3 shows a schematic block diagram of a conventional magnetic disk data reading device. Magnetization changes in a magnetic disk (not shown) are converted into voltage changes and amplified by the magnetic head 10. The read voltage is passed through the low pass filter 12.
, a differentiator 14 and a zero-volt comparator 16 to detect the peak, and a pulse shaper 18 to output the shaped data as read data 18a.

FIG. 4 shows a timing chart. As shown in FIG. 4(A), data is stored as inverted residual magnetization 22 within the disk plane 20, and when this data is read out by the magnetic head 10 via the low-pass filter 12, it is shown in FIG. 4(B). ) becomes a voltage waveform 12a. Since the magnetization reversal region has the maximum magnetic flux change, it corresponds to the peak of the voltage waveform 12a. The readout voltage waveform 12a is differentiated by the differentiator 14 to give the waveform 14a in FIG. 4(C), and when the zero volt comparator 16 cuts off voltages above zero volts, the waveform 16a in FIG. 4(D) is obtained. . This voltage waveform 16a is input to the pulse shaper 18 as a trigger and is shaped into a pulse having a specific time width as shown in FIG.
), and the magnetic data shown in FIG. 4(A) is read out.

[Problems to be Solved by the Invention] However, in conventional magnetic data reading devices, several problems have occurred when the reading resolution is increased. Figure 5 (C) and (D) are respectively Figure 4 (C) and
5(D) is a partially enlarged timing chart, and as shown in FIG. 5(C), a concave portion, so-called saddle 14b, is formed at the peak of the differential waveform 14a. This occurs because the change in the readout voltage is zero in the region where the magnetization is constant in FIG. As shown in Figure (D), the output 16a from the zero volt comparator 16 is not affected. However, when the resolution is increased, the saddle 14b reaches near zero volts as shown in FIG. 6, and therefore a reading error 16b occurs in the output 16a from the zero volt comparator 16 as shown in FIG. 6(D). There was a gap between the two.

As a measure to remove the saddle 14b, it has been proposed to provide a time domain filter between the differentiator 14 and the zero-volt comparator 16 and mask it for a predetermined period of time to remove the saddle 14b, but it is susceptible to noise and the masking time is However, there are also limitations, and no adequate improvement measures have been taken.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to provide a magnetic data reading device that is free from reading errors caused by saddles, has excellent noise resistance, and is capable of accurately reading data.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a boundary voltage detector that outputs a pulse signal when the read voltage of a magnetic head is equal to or higher than a predetermined boundary voltage, and a a clock regenerator that regenerates a clock using the pulse signal of the boundary voltage detector; a synchronization establisher that outputs the pulse signal from the boundary voltage detector in synchronization with the clock signal from the clock regenerator; It is characterized by the use of a pulse shaper that shapes the output synchronous pulse signal.

[Effect].

That is, a pulse signal corresponding to the peak of the read voltage of the magnetic head is generated by a boundary voltage detector, and a clock having a frequency higher than the fundamental frequency of data is reproduced using this pulse signal.

The pulse signal and the clock signal are input to a synchronization establisher to establish synchronization of the pulse signal and detect the peak of the read voltage.

Therefore, in the present invention, the conventionally used differentiator and zero-volt comparator are not used, and the read voltage of the magnetic head is all processed digitally, so there is no saddle problem and the influence of noise is extremely small.

[Embodiments] Hereinafter, preferred embodiments of the magnetic data reading device according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a magnetic data reading device according to the present invention, in which a read voltage from a magnetic head 10 that is in contact with a floppy disk (not shown) is passed through a low-pass filter 12 as a boundary voltage detector. It is input to a brass threshold comparator 30-1 which outputs a signal when the voltage is above the positive boundary voltage, and a negative threshold comparator 30-2 which outputs a signal when the voltage is below the negative boundary voltage. The signals from the comparator 30-1 and the comparator 30-2 are input to a clock regenerator 32 having a D-type flip-flop 34 and a tank circuit (not shown), and after being synchronized with the clock signal from the clock regenerator, pulse shaping is performed. The pulse is shaped by a monostable multivibrator 36 as a device and outputted via a NOR circuit 38.

FIG. 2 shows a timing chart for the configuration of FIG. 1. The voltage waveform after reading the magnetization change shown in FIG. 2(A) with a magnetic head and passing through the low-pass filter 12 is shown in FIG. 2(B), and this waveform is different from the conventional waveform shown in FIG. 4B. are the same.

The voltage waveform 12a in FIG. 2(B) is connected to the comparator 30-1.
When the voltage waveform 12a is inputted to
) becomes a pulse waveform 3O-1a as shown in FIG. On the other hand, since the voltage waveform 12a input to the comparator 30-2 is output only when the voltage is lower than the threshold voltage -VTH, it becomes a pulse waveform 3O-2a in FIG. 2(D).

When both pulse waveforms 3O-1a and 3O-2a are input to a tank circuit (not shown) of the clock regenerator 32, 3O-1a as shown in FIG. 2(E).

The clock 32a is reproduced at a frequency higher than the fundamental frequency of the magnetic data shown in FIG.
Output to.

Since the input signal acts on the D-type flip-flop 34-1.34-2 only when the clock signal arrives, the pulse waveform 3O-1 from the comparator 30-1.30-2
a, 3O-2a have constant pulse widths and are synchronized with the clock signal 32a, resulting in pulse waveforms 34-fa, 34-2a as shown in FIGS. 2(F) and (G), and the read voltage 12a is It can be seen that the peak is reliably detected.

The pulse waveforms 34-1a and 34-2a are further shaped into predetermined time pulses by the monostable multivibrator 36-1 and 36-2 to become pulse waveforms 36-1a and 36-2a, and finally pass through the NOR circuit 38. This becomes read data 38a.

In this way, the present invention provides the read voltage 12a of the magnetic head.
Instead of detecting peaks using the conventional differentiator and zero-volt comparator configuration, the peak voltage is detected using a boundary voltage detector, and the clock is regenerated and synchronized using its own data to perform peak detection. Since there is no influence of the saddle, and as can be seen from FIG. 2, the read voltage 12a is all processed digitally, data can be read with extremely little influence of noise.

Although a comparator is used as the boundary voltage detector in this embodiment, the present invention is not limited to this, and for example, a delta modulation circuit or the like may also be used.

Furthermore, the synchronization establisher is not limited to the D-type flip-flop of this embodiment, and it is of course possible to use, for example, a JK-type flip-flop or a 2-blip flop.

[Effects of the Invention] As explained above, according to the magnetic data reading device of the present invention, magnetic data reading is possible without reading errors caused by saddles during high resolution and with excellent noise resistance and accurate data reading. equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a magnetic data reader according to the present invention, FIG. 2 is a timing chart diagram of an embodiment of a magnetic data reader according to the present invention, and FIG. 3 is a conventional magnetic data reader. 4 is a block diagram of the device; FIG. 4 is a timing chart of a conventional magnetic data reading device; FIGS. 5 and 6 are partially enlarged timing charts of FIG. 4. 10...Magnetic head 12...Low pass filter 30-1...
・Comparator 30-2... Comparator 32... Clock regenerator 34-1...
D-type flip flop 34-2...D-type flip 70 tube 36-1...Monostable multivibrator 36-2...
・Monostable multivibrator 38・・・・・・・・・N
OR circuit

Claims (1)

[Scope of Claims] A magnetic data reading device that reads data by converting residual magnetization changes of a magnetic recording medium into voltage changes using a magnetic head, which outputs a pulse signal when a read voltage of the magnetic head is equal to or higher than a predetermined boundary voltage. a clock regenerator that regenerates a clock using the pulse signal from the boundary voltage detector; and a clock regenerator that synchronizes the pulse signal from the boundary voltage detector with the clock signal from the clock regenerator. a synchronization establisher that outputs a synchronization pulse signal; and a pulse shaper that shapes the synchronization pulse signal output from the synchronization establisher, and reads data by reliably detecting the peak of read voltage of the magnetic head. magnetic data reader.