JPH04330603A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To enable a detection of abnormality before the restoration of data becomes imposible due to the destruction of medium by a head crush, etc., and to improve a reliability as compared with a conventional manner. CONSTITUTION:The device is provided with an amplifier circuit 10 to amplify the output of a head amplifier 5 to an adequate level with a constant amplification rate and a level abnormality detecting circuit 11 to compare the output of this amplifier circuit 10 with the specified level value set beforehand and to generate the abnormality detecting signal for the display of an error when the output is decreased lower than the specified level value.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive.

0003

2. Description of the Related Art FIG. 3 shows an example of the configuration of a conventional magnetic disk device. As shown in the figure, in the magnetic disk device, data recorded on a medium 1 is read by a magnetic head 2. However, in this signal reading, a difference occurs in the level of the data signal from the magnetic head 2 depending on the inner circumferential portion and the outer circumferential portion of the data track. Therefore, an automatic gain control circuit (hereinafter referred to as AGC circuit) 3 is provided to automatically adjust the amplification factor and amplify the data signal from the magnetic head 2 to a predetermined level that can be read by the read circuit 4. is being carried out. In the figure, numeral 5 denotes a head amplifier, which amplifies the data signal from the magnetic head 2 to an appropriate size.

FIG. 4 shows an example of the output waveforms of each part in the above magnetic disk device. As shown in the figure, the output A of the head amplifier at the innermost circumference of the data track (when normal) is:
Head amplifier output B at the outermost circumference of the data track (
These AGC circuit outputs a and b are at the same level, although the level is lower than that in normal operation).

[0005]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional magnetic disk drive, even if an abnormality occurs in the head or the media, and the level of the waveform of the raw data obtained from the head becomes small, the AGC This abnormality cannot be detected because it is automatically amplified to a certain level, and by the time data cannot be read, a head crash has already occurred and the media is destroyed, making it impossible to recover the data. The problem is that it often becomes

For example, in the example shown in FIG. 4, the AGC circuit output c for the head amplifier output C, whose level has decreased due to so-called friction caused by the media being rubbed by the head or dust, is also at the same level as the AGC circuit outputs a and b during normal operation. It becomes. As a result, the rubbing progresses and a crash occurs when the board reaches the board, making it impossible to read data such as the head amplifier output D and the AGC circuit output d.

The present invention has been made in response to such conventional circumstances, and is capable of detecting an abnormality before the media is destroyed due to a head crash or the like and data cannot be restored. It is an object of the present invention to provide a magnetic disk device that can improve reliability as compared to the past.

[Configuration of the invention]

[0009]

[Means for Solving the Problems] That is, a magnetic disk device according to claim 1 includes a magnetic head section that reads data recorded on a medium, and a magnetic head section that automatically adjusts an amplification factor to read data from the magnetic head section. an automatic gain control section that amplifies the data signal to a predetermined level, and detects the level of the data signal from the magnetic head section;
The present invention is characterized by comprising a data signal level detection section that generates an abnormality detection signal when the level of the data signal falls below a predetermined value.

The magnetic disk drive according to claim 2 further includes a magnetic head section for reading data recorded on a medium, and a data signal from the magnetic head section that automatically adjusts an amplification factor to a predetermined level. and an amplification factor detection section that detects the amplification factor of the automatic gain control section and generates an abnormality detection signal when the amplification factor increases beyond a predetermined value. shall be.

[0011]

[Operation] In the magnetic disk drive of the present invention having the above structure, a decrease in the level of the data signal from the magnetic head section can be detected directly or indirectly through the amplification factor of the automatic gain control section. Therefore, an abnormality can be detected before the media is destroyed by a head crash or the like and the data cannot be restored, and reliability can be improved compared to the past.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a magnetic disk drive according to an embodiment of the present invention, and the same parts as those of the conventional magnetic disk drive shown in FIG. 3 are given the same reference numerals. The magnetic disk device of this embodiment includes an amplifier circuit 10 that amplifies the output of the head amplifier 5 to an appropriate level with a constant amplification factor;
Level abnormality detection circuit 1 which compares the output of this amplifier circuit 10 with a predetermined level value and generates an abnormality detection signal to display an error when the output falls below the predetermined level value.
1 is provided.

In the magnetic disk device of this embodiment having the above configuration, the data recorded on the medium 1 is transferred to the magnetic head 2.
The head amplifier 5 amplifies the data signal to an appropriate size. Then, the AGC circuit 3 automatically adjusts the amplification factor according to the output level of the head amplifier 5 to amplify the data signal to a predetermined level, and the read circuit 4 reads this data signal.

At the same time, the data signal amplified by the head amplifier 5 is amplified to an appropriate level by the amplifier circuit 10, and then compared with a predetermined level value by the abnormality detection circuit 11. It is constantly monitored whether the data signal from the head amplifier 5) has fallen below a predetermined level value. When the data signal drops below a predetermined level value, the abnormality detection circuit 11
An error detection signal generated from the error detection signal is used to display an error using a control device, a display device, etc. (not shown). Therefore, if the data signal level decreases due to rubbing etc., as in the case of the head amplifier output C shown in FIG. 4, for example,
This drop in the data signal level can be detected by an error display. Therefore, before the media is destroyed due to a head crash or the like and data cannot be restored, it is possible to stop using the media and perform data conservation and hardware maintenance.

Next, a magnetic disk drive according to another embodiment will be described with reference to FIG. In the magnetic disk drive of this embodiment, the amplification factor of the AGC circuit 3 is detected, and the AGC
An amplification factor detector 20 is provided which generates an abnormality detection signal and displays an error when the circuit 3 performs amplification exceeding a predetermined amplification factor. In this magnetic disk device, by constantly monitoring the amplification factor of the AGC circuit 3,
By indirectly monitoring the drop in the data signal level from the magnetic head 2 (head amplifier 5), it is possible to obtain the same effect as in the embodiment described above.

[0017]

[Effects of the Invention] As explained above, according to the magnetic disk device of the present invention, an abnormality can be detected before the media is destroyed due to a head crash or the like and data cannot be restored. , reliability can be improved compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a magnetic disk device according to another embodiment of the present invention.

FIG. 3 is a diagram showing the configuration of a conventional magnetic disk device.

FIG. 4 is a diagram for comparing and explaining output waveforms of each part of the magnetic disk device.

[Explanation of symbols]

1 Media 2 Magnetic head 3 AGC circuit 4 Lead circuit 5 Head amplifier 10 Amplifier circuit 11 Level abnormality detection circuit

Claims (2)

[Claims] 1. A magnetic head unit that reads data recorded on a medium; an automatic gain control unit that automatically adjusts an amplification factor to amplify a data signal from the magnetic head unit to a predetermined level; 1. A magnetic disk drive comprising: a data signal level detection section that detects the level of a data signal from a magnetic head section and generates an abnormality detection signal when the level of the data signal falls below a predetermined value. 2. A magnetic head unit that reads data recorded on a medium; an automatic gain control unit that automatically adjusts an amplification factor to amplify a data signal from the magnetic head unit to a predetermined level; A magnetic disk drive comprising: an amplification factor detection section that detects the amplification factor of the automatic gain control section and generates an abnormality detection signal when the amplification factor increases beyond a predetermined value.