JPS61273711A - Floppy disk device - Google Patents

Abstract

PURPOSE:To prevent an analog output signal from decreasing in level by detecting the replacement of a recording medium and power-on operation in a head unloaded state and feeding an alternating attenuating current to a head, and generating an alternating attenuating magnetic field in a head core and converging a magnetizing level on zero. CONSTITUTION:A recording circuit has a current source which feeds a current to the R/W head 1 and switches recording and magnetization erasure with a head erasing signal. A reproducing circuit 5 amplifies and processes the reproducing analog output signal of the R/W head 1 and outputs a digital reproducing signal. An erasure control circuit 6 has a power source which supplies a DC erasure current to an Er head 2 during recording and an alternating current for magnetization erasure to the Er head 2. When the power source is turned on in a head unloaded state, the alternating attenuating current is flowed to the R/W head 1 and Er head 2 while the heat is unloaded in recording medium replacement, and then the alternating attenuating current flows in the cores of the heads 1 and 2 and the magnetism level of the core decreases according to the attenuation of magnetic flux and converges on the zero level, so the magnetism of the heads 1 and 2 are minimized. Consequently, asymmetry is prevented from deterioration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a floppy disk drive, and more particularly to eliminating the adverse effects of head magnetization on analog output signals.

[Background of the invention]

Recently, high coercive force recording media for 1.6 MB and 1. Floppy disk devices capable of recording and reproducing both OMB low coercive force recording media are attracting attention. When recording and reproducing recording media having different coercive forces He with the same head, various problems occur. In particular, 1. When recording and reproducing a low coercive force recording medium for OMB, if the head goes off track and busses, or if the head sweeps over the data track, a phenomenon occurs in which the data recording state is attenuated and the analog output signal level is reduced. A general introduction to the floppy disk device, which has become a big problem, includes Shoji Takahashi's Latest Floppy Disk Device and Its Application Know-how, published by JCQ Publishing.

[Purpose of the invention]

An object of the present invention is to provide a floppy disk device in which the analog output signal level does not decrease even when recording media having different coercive forces are shared.

[Summary of the Invention] After investigating the cause of the phenomenon of decrease in analog output signal level, the inventors reached the following conclusion. That is, since a high remanence Br ferrite material is used as the head core material for recording, reproducing and erasing on a 1.6 MB high coercive force recording medium, the erasing head generates a DC magnetic field using a DC current, and when the recording current ends. It is presumed that the above phenomenon occurs because the magnetization of the recording/reproducing head increases when either one of the heads is energized.

Therefore, it is thought that if the magnetization of the recording/reproducing head and the erasing head is removed every time the recording medium is changed, the phenomenon of decrease in the analog output signal level can be eliminated.

The feature of the present invention is to detect that the recording medium has been replaced and that the power is turned on with the head unloaded, and to apply an alternating attenuating current to the head to generate an alternating attenuating magnetic field within the head core. The point is to converge the magnetization level within to zero.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a recording/reproducing system of a floppy disk device. In the figure, 1 is the R/W head for recording and reproduction, 2 is the Er head for erasing, and 3 is the R/W switching circuit of the R/W head 1, which performs the logical sum of the R/W switching signal and the head erase signal. The recording circuit 4 or the reproducing circuit 5 is selected depending on the output from the OR circuit 7. The recording circuit 4 has a current source that processes an input digital signal and converts it into an inverted recording current, generates an alternating attenuation current for head magnetization/erase, and supplies current to the R/W head 1.

Recording and magnetization erase are switched by a head erase signal. The reproducing circuit 5 amplifies and processes the reproduced analog output signal of the R/W head 1 and outputs a digital reproduced signal. Reference numeral 6 denotes an erase control circuit, which has a power supply for supplying a DC erase current to the Er head 2 during recording and for supplying an alternating attenuation current for magnetizing erase of the Er head 2 to the Er head 2, and a R/W switching circuit. The two are switched by a head erase signal and a head erase signal. 8 is a recording medium exchange detection section. Reference numeral 9 denotes a power-on detection unit that detects that the power is turned on while the head 1.2 is not loaded with a recording medium. The output of an OR circuit 10 which takes the logical sum of the outputs of the power supply rise detection section 9 and the recording medium replacement detection section 8 becomes a head erase signal. 11 indicates the head to be demagnetized by R.
/W head 1 or Er head 2 or both.

Conventionally, if either or both of the R/W head 1 and the Er head 2 were magnetized for some reason, the R/W head 1 would be in a DC biased state, making it impossible to record and reproduce in the correct magnetization reversal state during recording and reproduction. , the asymmetry was getting worse. In addition, the residual magnetic flux Br (
When heads 1 and 2 sweep over the data track, it may attenuate the data recording state and lower the reproduction output voltage of R/W head 1, or it may affect the magnetization direction of the data and reduce the reproduction output. This increased voltage asymmetry and worsened the asymmetry.

In contrast, in this embodiment, when the power is turned on with the head unloaded, and while the head is in the unloaded state when replacing the recording medium, an alternating attenuating current is applied to the R/W head 1 and the Er head 2. , an alternating damped magnetic flux flows in the cores of heads 1 and 2.

As shown in Figure 2, as the current or magnetic flux attenuates, the magnetization level of the core decreases in the order of 1 → 2 → 3... → 12 and converges to zero level, so the magnetization of heads 1 and 2 decreases. Minimum. In this way, the problem caused by magnetization of the head can be fundamentally solved.

The effect of the alternating decay current is the same whether it is a pulse waveform as shown in FIG. 3(A) or an analog waveform as shown in FIG. 3(B).

Also, since the head is degaussed before being loaded onto the media,
Magnetization can be demagnetized without inadvertently erasing recorded data.

Further, since the head to be demagnetized can be selected by the switch 11, only the head which has a large amount of magnetization and which attenuates the recording state of the medium can be demagnetized.

(Effects of the Invention) According to the present invention, since the magnetization of the recording/reproducing head and the erasing head can be minimized, it is possible to minimize the magnetization of the recording/reproducing head and the erasing head. Since deterioration of asymmetry, which is an increase in the asymmetry of the reproduced output voltage, is prevented, a highly reliable floppy disk device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a recording/reproducing system according to an embodiment of the present invention, and FIG. 2 is a B-H characteristic diagram of a Herad core. FIG. 3 is a diagram showing an example of the waveform of the head magnetization/erasing current. 1.-- Recording/reproducing head, 2... Erasing head, 3
...R/W switching circuit, 4...recording circuit, 5...reproducing circuit, 6...erasing control circuit, 7...OR circuit, 8
...Recording media agent Patent attorney Katsuo Ogawa −゛−′ 1st layer 20

Claims (1)

[Claims] 1. In a floppy disk device that shares recording media with different holding powers and includes a digital signal recording/reproducing head, its recording/reproducing switching circuit, and a signal erasing head and its erasing control circuit, both circuits In addition to having a built-in power supply for supplying an alternating attenuation current to each head, a recording medium exchange detection section is also provided, and when an exchange of the recording medium is detected, an alternating attenuation current is supplied to at least one of the recording/reproducing head and the erasing head. A floppy disk device characterized in that the magnetization of the head is erased. 2. In claim 1, the power supply rise detection unit includes a power supply start-up detection unit, and indicates that the power supply is turned on with the medium exchange detection signal from the recording medium exchange detection unit and the head in an unloaded state. A floppy disk device characterized in that an alternating attenuating current is applied to at least one of both heads in response to at least one of the signals from the floppy disk, thereby erasing magnetization of the head. 3. A floppy disk device according to claim 1 or 2, characterized in that it is provided with a switch for selecting a head whose magnetization is to be erased.