JPS62129907A - Data reproducing device for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To indicate the occurrence of abnormality to a user and to deal with the abnormality by indicating the occurrence of abnormality when the readout signal of a head output circuit drops in level abnormally and raising the level of the readout signal to its normal level. CONSTITUTION:The readout signal of the head output circuit 11 of a data reproducing device is processed by differential amplification 12, AGC 13, and smoothing 14, and the result is inputted to a voltage follower amplifier 15. The readout signal from this amplifier 15 is applied to a comparator 20 and compared with a preset reference level, thereby outputting an abnormality detection signal E when the readout signal is lower than the reference level. This signal E is latched by a CPU 22 through an FF 21 and a display device 23 and a gain control circuit 24 are operated according to the signal E. Then, the display device 23 indicates the occurrence of abnormality and a control circuit 24 controls the gain of the differential amplification 12 to raise the gain to a specific value from the normal value, thus dealing the occurrence of the abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention particularly relates to a data reproducing device for a magnetic recording/reproducing device, which is a hard disk device.

[Technical Background of the Invention and Problems Therewith] Conventionally, a hard disk device reproduces recorded data from a magnetic recording medium (hereinafter referred to as a disk) 10 using a data reproducing circuit as shown in FIG.

The data reproduction circuit includes a differential amplifier 12, an AGC circuit 13,
It includes a smoothing circuit 14 and a voltage follower amplifier 15. The differential amplifier 12 amplifies the read signal output from the head output circuit 11 and outputs it to the AGC circuit 13. The head output circuit 11 is an integrated circuit that outputs a read signal extracted from the disk 10 by the magnetic head.

The AGC circuit 13 is an automatic gain adjustment circuit whose gain is adjusted by the control voltage VC output from the voltage follower amplifier 15. The smoothing circuit 14 converts the read signal output from the AGC circuit 13 into a DC voltage signal and outputs it to the voltage follower amplifier 15. Here, the AGC circuit 13 is a circuit that keeps the level of the read signal constant by adjusting gain, and outputs its output signal to the data discrimination circuit. The data discrimination circuit creates a data pulse from the read signal and outputs it as reproduction data of the recorded data.

By the way, the G circuit 13 always outputs a signal at a constant level as the continuous signal when the level of the continuous signal from the differential amplifier 12 is within a predetermined range. At this time,
When the level of the read signal from the magnetic head drops below the reference level due to deterioration of the head output circuit 11 or the like, the AGC circuit 13 may not operate normally. Therefore, it may become impossible to read recorded data from the disc 10.

"Objective of the Invention" An object of the present invention is to be able to notify the user of the occurrence of an abnormality when an abnormality occurs in the head output circuit, etc. and the level of the readout signal drops abnormally, and to make it possible to indicate that the readout signal at the time of the abnormality is normal. An object of the present invention is to provide a data reproducing device for a first recording/reproducing Pi device that can reproduce recorded data.

[Summary of the Invention] The present invention provides a read signal amplifying means for amplifying a read signal with a predetermined gain, an abnormality detecting means for detecting the occurrence of an abnormality in the read signal output means, and an abnormality processing means for performing abnormality processing when an abnormality occurs. and gain control means for increasing the gain of the read signal amplification means in accordance with abnormality processing.

The abnormality detection means compares the read signal output from the read signal amplification means with a normal level signal, and outputs an abnormality detection signal if the read signal level is an abnormal level.

When the abnormality processing means receives the abnormality detection signal from the abnormality detection means, it instructs the occurrence of an abnormal situation and outputs a control signal instructing to increase the gain of the read signal amplification means. The gain control means is configured to set the gain of the read signal amplification means to a predetermined value increased from a normal value in response to an ilJ control signal from the abnormality processing means.

With this configuration, when an abnormality occurs and the level of the read signal drops, the level of the read signal is raised to within the allowable range, and normal recorded data is reproduced from the read signal output when the abnormality occurs. becomes possible.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing the configuration of a data reproducing device according to an embodiment. In FIG. 1, the comparator 20 compares the level of the read signal from the voltage follower amplifier 15 with a reference signal at a preset reference level (normal level), and detects an abnormality if the read signal is at a level lower than the reference level. Outputs signal E. Flip-flop 21 latches the abnormality detection signal E output from comparator 20. The microprocessor (CPtJ) 22 is a control circuit that performs abnormality processing when an abnormality occurs, and generates control signals that operate the display 23 and the gain control circuit 24 in response to the abnormality detection signal E output from the flip-flop 21. Output. The display 23 is a circuit that displays an indication of the occurrence of an abnormality.

The gain control circuit 24 is a control circuit that increases the gain of the differential amplifier 12 from normal to a predetermined value when an abnormality occurs.

Note that the other configurations are the same as those shown in FIG. 3, so the same reference numerals are given and the explanation will be omitted.

Next, the operation of this embodiment will be explained. First, disk 10
Assume that when a read operation of the magnetic head is performed on the magnetic head, a read signal of a normal level is output from the head output circuit 11. At this time, the AGC circuit 13 functions normally as described above and outputs a read signal of a constant level to the data discrimination circuit. At this time, since the level of the output signal of the voltage follower amplifier 15 is also normal, the output of the abnormality detection signal E from the comparator 20 is stopped. As a result, since the gain control circuit 24 is in a non-operating state, the differential amplifier 12 is set to the head output circuit 1 with the normal setting gain.
Amplify the read signal from 1.

Here, the differential amplifier 12 and the gain control circuit 24 are
Specifically, it is configured as shown in FIG. 2, for example.

As described above, if the level of the read signal from the head output circuit 11 is normal, the output of the control signal from the CPU 22 is stopped, and the gain control circuit 24 is in an inactive state. That is, as shown in FIG. 2, the field effect transistor (FET) Q3. Q4 is in the off state. Therefore, the gain G of the differential amplifier 12
is determined as shown in equation (1) below under normal conditions.

G=R2/(R1+Re)-(1) Here, Re is the emitter resistance value of the transistor Q1.

Next, assume that the head output circuit 11 has deteriorated and the level of the read signal output from the head output circuit 11 has fallen below a normal level. This low level read signal is
Smoothing circuit 1 through differential amplifier 12 and AGC circuit 13
Output to 4. The level of the DC voltage signal output from this smoothing circuit 14 through the voltage follower amplifier 15 is also
The level is lower than the normal level. Comparator 2
0 means that the level of the read signal from the voltage follower amplifier 15 is lower than the reference level, so the abnormality detection signal E
Output. The flip-flop 21 is a comparator 2
The abnormality detection signal E from 0 is latched.

The CPU 22 recognizes that an abnormality has occurred based on the abnormality detection signal E latched by the flip-flop 21, and executes abnormality processing. That is, the CPU 22
3 to execute a display instructing the occurrence of an abnormality. This allows the operator to confirm that the level of the successive output signal from the head output circuit 11 has decreased abnormally.

Furthermore, the CPU 22 operates the gain control circuit 24. That is, as shown in FIG. 2, FETQ3. of the gain control circuit 24 is controlled by a control signal from the CPU 22. Q4
turns on. Thereby, the gain control circuit 24 changes the gain of the differential amplifier 12 from the normal gain to the increased gain. The gain G of the differential amplifier 12 when such an abnormality occurs is determined as shown in equation (2) below.

G=R27' (R1, //R5+Re)-(2) Here, R1/, /R5 have values as shown in the following formula (3).

R1//R5=R1/ (R1+R5)...(3> Or, the gain G of the differential amplifier 12 is G = R4/'
(R3//R6+ Re ) −(4).

In this equation (4), Re is the emitter resistance value of the transistor Q2.

Therefore, when an abnormality occurs, the gain control circuit 24 sets the differential amplifier 12 to a higher gain than normal, and the read signal from the head output circuit 11 is amplified by this gain.

In this way, due to deterioration of the head output circuit 11,
When the level of the read signal from the head output circuit 11 drops abnormally, the comparator 20 outputs an abnormality detection signal E. In response to the output of this abnormality detection signal E, the display 2
3 is displayed to instruct the operator that an abnormality has occurred. Therefore, the operator can confirm that an abnormality has occurred in the head output circuit 11, etc., and immediately stop the operation of the disk device and have it repaired.

Furthermore, when an abnormality occurs, the gain of the differential amplifier 12 can be increased compared to normal. Therefore, the low level read signal output when an abnormality occurs can be raised to a normal level. Therefore, a read signal at a normal level can be output from the AGC circuit 13 to the data discrimination circuit, and normal recorded data can be reproduced.

[Effects of the Invention] As detailed above, according to the present invention, when an abnormality occurs in the head output circuit or the like in a hard disk drive and the level of the read signal drops abnormally, the occurrence of the abnormality is indicated and the abnormality is detected. The level of the read signal at the time of generation can be raised to a normal level.

Therefore, it is possible to instruct the user about the occurrence of an abnormality, and
Normal recorded data can be reproduced from the read signal when an abnormality occurs. This makes it possible to reliably obtain recorded data when an abnormality occurs, and to appropriately deal with the occurrence of an abnormality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a data reproducing device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the specific configuration of the differential amplifier and gain control circuit of the same embodiment, and FIG. 1 is a block diagram showing the configuration of a conventional data reproducing device. 11... Head output circuit, 12... Differential amplifier, 2
0... Comparator, 22... CPU, 23...
Display, 24...gain control circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Scope of Claims] In a data reproducing device of a magnetic recording and reproducing device that reproduces recorded data based on a read signal reproduced from a magnetic recording medium by a magnetic head, the read signal outputs the read signal extracted by the magnetic head. output means; read signal amplification means for amplifying the read signal outputted from the read signal output means with a predetermined gain; and a read signal amplified means that compares the read signal output from the read signal amplification means with a normal level signal and outputs the read signal. an abnormality detection means that outputs an abnormality detection signal if the level is abnormal; and a control signal that instructs the occurrence of an abnormal situation and increases the gain of the read signal amplification means when receiving the abnormality detection signal from the abnormality detection means. and a gain control means for setting the gain of the read signal amplifying means to a predetermined value increased from a normal value in response to a control signal from the abnormality processing means. Data reproducing device for magnetic recording and reproducing device.