JPH01276405A - Magnetic recording and reproducing system - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording and reproducing system, which can record the information of much more quantity by including an alternative current erase magnetizing part to a magnetic medium at the time of recording and keeping the presence and absence of a peak and the three types information of a polarity to a signal voltage at the time of reproducing. CONSTITUTION:When a head current corresponding to an alternative current erasing current flows, an enable signal EN from a control circuit 12 goes to an H level. At such a time, an AND gate 13 is closed and an AND gate 14 is opened. Then, an alternative current in the frequency of a pulse generating circuit (11) flows to the coil of a magnetic head 1. Accordingly, when the enable signal EN is outputted from the control circuit 12 with suitable timing, the head current as shown in a figure (G) can flow. The operation of an information reproducing circuit 20 is as follows. When reference voltages eA and eB of comparators 21 and 22 are set as shown in a figure, output voltages at an M-point and an N-point as shown in figures (H) and (I). Accordingly, by using such a device, not only the peak position of a reproducing signal but also the polarity of the peak can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a magnetic recording and reproducing method for recording and reproducing information, particularly digital information, on a magnetic medium.

[Prior Art] Figures 5 and 6 show conventional magnetic recording, such as those shown in Figures 1 and 7 (a) of ``Theory of Magnetic Recording'' (by Masaaki Nishiyo, Chosen Shoten, 1985). FIG. 2 is an operation explanatory diagram for explaining information recording and reproducing operations performed by the apparatus.

In the figure, (1) is a magnetic head consisting of a core (la), a coil (1b), and a gap (lc), and (2) is a magnetic head that flows through the magnetic head (1) during recording and plays back current according to the recorded data. Sometimes there is a recording/reproducing amplifier circuit that processes the reproduction signal from the magnetic head (1) and restores information, (3) is a recording information generation circuit, (4) is a signal line, (5) is a magnetic medium for recording information, (A) is a magnetization status diagram showing the direction of saturation magnetization in the magnetic medium (5) with arrows, (B) is recorded information, (C)
is the head current flowing through the coil (1b), (D) is the magnetic flux passing through the core (1a) during reproduction, and (E) is the head current flowing through the core (1a).
) is the reproduction signal voltage generated across the coil from the time change of the magnetic flux passing through the coil, and (F) is the reproduction information obtained from the reproduction signal voltage (E).

Next, the operation will be explained. First, when recording information,
For example, if it is determined that the head current flowing through the coil is reversed at the 141 I+ position, the magnetic flux passing through the air gap (1c) at the 1'' position will be Corresponding to the direction of the magnetic flux, the direction of saturation magnetization on the magnetic medium (5) is determined, forming a row of magnetization reversals.

Next, when reproducing information, the magnetic medium (5) is moving relative to the magnetic head (1), and the position where the direction of saturation magnetization on the magnetic medium (5) is reversed, that is, the magnetization transition position. Then, the magnetic flux passing through the core (la) changes rapidly. As a result, a reproduction signal voltage is generated across the coil (1b).

By detecting the peak position of this reproduced signal voltage, the transition position of the saturation magnetization direction on the magnetic medium (5) can be determined.
Therefore, since the position of 1 (I11) of the recorded information is known, the recorded information can be reproduced.

[Problems to be Solved by the Invention] The conventional recording and reproducing system is configured as described above, and the peaks of the reproduced signal voltage always appear with alternating positive and negative polarities, so the reproduced signal has a 'signal peak'. Only two types of information could be held: "and" there is no signal peak."

If it is possible to freely output either the positive or negative polarity of a signal peak, then there are three types of signal peaks: ``a positive peak exists'', ``a negative peak exists'', and ``no peak exists''. If the magnetic medium (5) is magnetized to generate N signal peaks in a certain area of the magnetic medium (5), log, 3''
= Nlog, maximum approximately 1.6 from 3 clauses 1.585N
It can accommodate N amount of information. However, in the conventional method, only two types of information can be held as described above, so in the above case, log22 '' = N log
, 2 = H, and there was a problem that the information recording density could not be increased.

This invention was made to solve the above-mentioned problems, and it is a magnetic recording and reproducing method that can store three types of information on a magnetic medium and record a larger amount of information than before. The purpose is to obtain.

[Means for Solving the Problems] The magnetic recording and reproducing method according to the present invention applies magnetization of a first polarity, magnetization of a second polarity opposite to this, or AC erase magnetization to recorded information on a magnetic medium. An information recording circuit that switches and outputs information as appropriate, detects the transition position between different magnetizations of the magnetic medium, detects the polarity of the peak value of the reproduced signal voltage generated in response to the detection, and has three types of information. and an information reproducing circuit for obtaining a reproduced signal.

[Function] In the magnetic recording and reproducing method of the present invention, during recording, a part of the magnetic medium includes an AC erasing magnetized portion, so that during reproduction, two peaks with the same polarity occur in succession in the reproduced signal voltage. As a result, it is possible to extract a reproduced signal containing three types of information: presence or absence of a peak in the reproduced signal voltage and its polarity.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure is an operation explanatory diagram for explaining information recording and reproducing operations according to an embodiment of the present invention.
) Magnetization status diagram showing the direction of saturation magnetization with arrows, (D)
is the head core magnetic flux during reproduction, (E) is the reproduction signal voltage, (G) is the head recording current, and t0 to tztta
The head recording current between ~t3tt4~tstts~t7 is an AC erase current.

When the magnetic medium (5) is magnetized by an AC erasing current,
The direct current magnetization is erased and the magnetization in that area effectively becomes zero for the magnetic head. Therefore, the magnetic flux passing through the core of the magnetic head (1) during reading becomes as shown in (D).

The reproduced signal voltage corresponds to the time differential of the magnetic flux (D), and is expressed as E).

As described above, according to the recording and reproducing method according to the present invention, since the magnetization state of the magnetic medium effectively creates an O state for the magnetic head, up to two consecutive peaks of the reproducing signal voltage having the same polarity can be generated. It becomes possible to do so.

Therefore, by detecting the polarity of the peak of the reproduced signal during reproduction, more information can be extracted within the same area than in the conventional method.

Next, a second example of a device that realizes the recording method described above will be described.
This will be explained with reference to FIGS. 3 and 4.

FIG. 2 shows an information recording circuit (1) in an embodiment of the present invention.
0), FIG. 3 is a circuit diagram showing the information reproducing circuit (20), and FIG. 4 is a signal waveform diagram illustrating the operation of the information reproducing circuit (20). In the figure, (1) is a magnetic head, (2) is a recording/reproduction amplifier circuit, (3) is a recording information generation circuit, (11) is a pulse generation circuit that generates a pulse signal corresponding to an AC erasing signal, (12) is an enable signal (
EN), (13) and (14) are AND gates, (15) is an inverter, (16) is an OR gate, and (21) is, for example, a practical electronic circuit handbook (Transistor Technology Editorial Department Line, CQ Publishing). Company, 1972
(22) is a comparator that receives a positive voltage eA as a reference voltage and detects a positive peak above this value, as shown in Figure 8-31 of 2010). A comparator that detects negative polarity peaks that are input and less than or equal to this value.

(E) is a reproduction signal voltage, (H) is a positive peak position pulse signal obtained by pulsing the detected positive polarity peak, and (I) is a negative peak position pulse signal obtained by pulsing the detected negative polarity peak.

Next, the operation will be explained. When flowing the same head current as before, the enable signal (EN
) to L level. Then and gate (14)
is closed, and the AND gate (13) is opened, performing the same operation as before. When a head current corresponding to an AC erasing current flows, an enable signal (E
N) becomes H level. At that time, and gate (13
) is closed, the AND gate (14) is opened, and an alternating current at the frequency of the pulse generating circuit (11) flows through the coil of the magnetic head (1). Therefore, the control circuit (12)
By outputting an enable signal (EN) at an appropriate timing, a head current as shown in FIG. 1 (Gi) can be caused to flow.

Next, the operation of the information reproducing circuit (20) will be explained with reference to FIG. Here, comparator (21), (2,2)
(7) If the reference voltages 8A and 8B are set as shown in the figure, the output voltages at points M and N in Figure 3 will be, respectively,
(H) (I). Therefore, according to this device, it is possible to detect not only the peak position of the reproduced signal but also the polarity of the peak.

[Effects of the Invention] As described above, the present invention provides an information recording method in which magnetization of a first polarity, magnetization of a second polarity opposite to the first polarity, or AC erase magnetization is selectively applied to a magnetic medium according to recorded information. Information reproduction that detects the transition position between different magnetizations of the circuit and the magnetic medium and detects the polarity of the peak value of the reproduction signal voltage generated in response to the detection to obtain a reproduction signal having three types of information. Since it is equipped with a circuit, it has the effect that a larger amount of information can be recorded in the same recording area of a magnetic medium compared to the conventional one.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is an explanatory diagram of its operation, FIG. 2 is a circuit diagram showing its information recording circuit, and FIG. 3 is its information reproducing circuit. FIG. 4 is a signal waveform diagram explaining the operation of the information reproducing circuit, and FIG.
6 and 6 are operation explanatory diagrams for explaining information recording and reproducing operations by a conventional magnetic recording device. In the figure, (1) is a magnetic head, (2) is a recording/reproduction amplifier circuit, (3) is a recording information generation circuit, (5) is a magnetic medium, (10) is an information recording circuit, and (11) is an AC erase signal. Generation circuit (pulse generation circuit), (12) is a control circuit, (
13). (14) is an AND gate, (15) is an inverter, (1
6) is an OR gate, (20) is an information reproducing circuit, (21
) is a positive peak detection circuit (comparator), (22)
is a negative polarity peak detection circuit (comparator), (A) is a diagram of the magnetization state in the magnetic medium, (D) is the head core magnetic flux during reproduction, (E) is the reproduction signal voltage, (G) is the head recording current, (E ) is the reproduction signal voltage, (H) is the positive peak position pulse signal, and (I) is the negative peak position pulse signal. The same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] In a magnetic recording and reproducing method in which information is recorded by magnetizing a magnetic medium by passing a recording current through a magnetic head, and reproducing information by detecting the magnetization transition position of the magnetic medium, a first polarity of magnetization, an information recording circuit that appropriately switches and applies magnetization of a second polarity of opposite polarity or AC erasure magnetization to the magnetic medium according to recorded information; and detecting a transition position between different magnetizations of the magnetic medium; 1. A magnetic recording and reproducing system comprising: an information reproducing circuit that detects the polarity of a peak value of a reproducing signal voltage generated in response to a reproducing signal and obtains a reproducing signal having three types of information.