JPH01137409A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To use magnetic disks and magnetic head which cannot be used in a conventional device by changing the degree of compensation of an equalizer in accordance with the variation of characteristics of magnetic disks and magnetic heads. CONSTITUTION:When a head disk assembly (HDA) discrimination signal as a first output signal is inputted to a level detector 2, equalizer control signals 102 and 103 are turned on/off in accordance with the value of an HDA discrimination resistance. A reproduced signal 105 obtained by amplifying a reproduced signal 104 as the other output of an HDA 1 by an amplifier 3 is inputted to an equalizer 4, and the equalizer switches the degree of waveform compensation in accordance with equalizer control signals 102 and 103 and outputs a waveform compensated reproduced signal 106 to a peak detector 5. The peak detector 5 outputs a peak pulse 107 corresponding to the peak position of the waveform compensated reproduced signal 106 inputted to the peak detector 5. Thus, magnetic heads and magnetic disks which cannot be used in a conventional device can be used.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic disk device.

[Conventional technology]

Conventionally, this type of magnetic disk drive compensates the reproduced waveform using an equalizer (waveform equalizer) that has a certain value by aligning the characteristics of the magnetic head and magnetic disk within a specified range. was.

[Problem that the invention seeks to solve]

However, if each characteristic of the magnetic head or magnetic disk deviates from the specified range due to lot variations or the like, the respective magnetic head or magnetic disk will have loft defects and become unacceptable as a product. If a 100% inspection is performed to select magnetic heads and magnetic disks that are within a specified range, there is a drawback that a large amount of loss is generated.

Furthermore, when each characteristic is located near the limit of the specified range, one compensation by the equalizer also deviates from the optimum value, resulting in over-compensation or under-compensation, which reduces the reliability of stored data.

[Means for solving problems]

The magnetic disk device of the present invention is a magnetic disk device having an HDA having a structure in which a magnetic disk and a magnetic disk are sealed. It is characterized by having a level detector that detects the resistance value of the resistor, and an equalizer that switches constants based on the output of the level detector.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

HDA identification signal 101, which is the first output of HDA assembly (HDA) 1, is input to level detector 2, and equalizer control signal 102,1 which is the output of level detector 2 is inputted to level detector 2.
03 is input to the equalizer 4. A reproduced signal 104, which is another output of the HDAI, is input to the amplifier 3, and an amplified reproduced signal 105, which is the output of the amplifier 3, is input to the equalizer 4. A waveform-compensated reproduced signal 106, which is the output of the equalizer 4, is input to the peak detector 5, and a peak pulse 107, which is the output of the peak detector 5, is sent to a subsequent data demodulation circuit (not shown).

The HDA identification resistor built into the HDAI has one end grounded and the other end connected to the first output terminal.

When the HDA identification signal 101, which is the first output signal, is input to the level detector 2, the equalizer control signal 102°103 is changed to 0N10FF according to the value of the HDA identification resistor.

Equalizer 4 is the reproduction signal 10 which is the other output of HDAI.
4 is amplified by the amplifier 3, the amount of waveform compensation is switched in accordance with the equalizer control signals 102 and 103, and the signal is sent to the peak detector 5 as a waveform-compensated reproduced signal 106. Output. The peak detector 5 outputs a peak pulse 107 corresponding to the peak position of the waveform-compensated reproduced signal 106 that is input thereto.

FIG. 2 shows an example of a detailed circuit diagram of the level detector 2 and equalizer 4 in the block diagram of FIG. 1.

HDA identification resistor R1 built in HDAI has one end grounded and the other end connected to the output terminal of HDAI.
The identification signal 101 is connected to the power supply Vcc via the resistor R21 of the level detector 2 and the voltage comparator 21.2.
2. Voltage comparator 21.2
The connection points of resistors R22, R23, and R24 connected in series between Vcc and ground are connected to the second input terminal of No.2. Equalizer control signals 102 and 103, which are the outputs of voltage comparators 21 and 22, are connected to control terminals of switches 43 and 44 of h equalizer 4, respectively.

The amplified reproduction signal 105, which is input to the equalizer 40, is grounded via resistors R41 and R42, and the delay line 4
Connected to 1. Resistors R43, R44 and an amplifier W42 are connected to the connection point between the resistors R41 and R42. The output of delay line 41 is connected to the input of amplifier 42. Resistor R4
3 and R44 are connected to one terminal of switches 43 and 44, respectively, and the other terminals of switches 43 and 44 are connected to each other.

The voltage of the HDA identification signal 101 is determined by resistors R21 and R1, and if this voltage is 1°1, that is, Vl corresponds to the value of the HDA identification resistor. A value of 1 is determined. The second input terminal voltage of the voltage comparator 21.22 is connected to the resistor R22, R
23, R24 and the voltages are V□, ■, respectively.
Therefore, V. 1 and V□,■! ! By comparing the values of , three types of HDA identification resistances can be identified.

In the case of v1□>v21, the voltage comparator 21.22 is turned ON, and the switch 43.44 is turned ON (the switch is closed) as the equalizer control signal 102, 103 -Vl
1>Vl. t>V! ! In the case of voltage comparator 21
is OFF, voltage comparator 22 is ON, and switch 43 is turned OFF.
OFF (switch opens), switch 44 is turned ON - V * x > V t. If it is 1, the voltage comparators 21 and 22 are turned off, and the switches 43 and 44 are turned off.
Make it F.

In the equalizer 4, an amplifier 42 is connected via a delay line 41.
The main signal is input to the amplifier 42, and the compensation signal is input to the amplifier 42 via the resistor R41. The compensation signal is a signal whose timing is shifted from the main signal by a delay time determined by the delay line, and whose voltage level is smaller than that of the main signal by the voltage division ratio determined by the resistors R41 to R44.

It is possible to change the degree of compensation by changing the ratio of the voltage level of the compensation signal to the main signal. For example, if the frequency characteristics of a magnetic head or magnetic disk deteriorate, the characteristics can be changed by increasing the degree of compensation. It is possible to compensate for the deterioration in Conversely, if the frequency characteristics improve, overcompensation can be prevented by weakening the degree of compensation.

In this embodiment, there are three types of HDA identification, but it is also possible to set two or four or more types. Further, in this embodiment, the voltage level is switched to switch the compensation amount of the equalizer, but more optimal compensation can be achieved if the delay time is also switched in combination.

〔Effect of the invention〕

As explained above, the present invention enables the use of magnetic disks and magnetic heads that were previously unusable by changing the degree of compensation of the equalizer in response to variations in the characteristics of the magnetic disks and magnetic heads. This not only results in significant cost reduction, but also allows the degree of compensation to be set according to characteristics, which has the effect of improving the reliability of stored data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a circuit diagram showing details of the level detector and equalizer shown in FIG. 1. 1... HDA12... Level detector,
3...Amplifier, 4...Equalizer, 5
...Peak detector, 21.22...Voltage comparator, 41...Delay line, 42...
Amplifier, 43, 44...Switch, R1...
...HDA identification resistor, R21-R24, R41-R4
4...Resistance. Agent: Patent Attorney Shinatsu Uchihara (once)

Claims (1)

[Claims] In a magnetic disk drive having a head disk assembly having a structure in which a magnetic head and a magnetic disk are sealed, an identification resistor having one end grounded and the other end connected to an output terminal inside the head disk assembly, and a resistance value of the identification resistor. 1. A magnetic disk drive comprising: a level detector for detecting the magnetic head; and a constant of an equalizer for compensating a reproduced waveform from the magnetic head is switched based on the output of the level detector.