Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Reexamination Certificate
1999-08-30
2002-04-23
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
C360S323000, C360S068000, C360S061000
Reexamination Certificate
active
06377411
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a head integrated circuit (IC), a head amplifier circuit, a head suspension assembly, and a magnetic disk drive for avoiding electrostatic breakdown of a magnetic head.
With conventional magnetic disk drives having built-in head suspension assemblies (HSA) each including a suspension on which a head is mounted, it is a standard practice to mount a head amplifier circuit including a read amplifier circuit which amplifies a signal read by the head from a magnetic recording medium, and a write driver circuit which allows the head to write data onto the magnetic recording medium by reversing a direction of current flow to the head, on a flexible printed circuit board (FPC) as a cabling member for interconnections.
The FPC (hereinafter referred to as the main FPC) is formed on top with a pattern of conductive interconnections connected with input/output terminals of the head amplifier circuit. On the opposite side of the interconnections to the head amplifier circuit are formed connection pads which correspond in number to head suspension assemblies (HSAs) used.
To each HSA is fixed a relay FPC which connects the electrodes of the corresponding head attached to its end with a preamplifier circuit through the main FPC. The relay FPC is formed with a pattern of interconnections which are connected at its one end with the electrodes of the corresponding head. The other end of the relay FPC forms a soldering portion consisting of electrode pads connected with the pattern of interconnections. The relay FPC is electrically and mechanically connected with the main FPC by soldering together each electrode pad of the relay FPC and a corresponding one of the connection pads of the main FPC.
Since the FPC has excellent flexibility, the movement of the head along the surface of a magnetic recording medium does never adversely affect the state of connection of the head with the head amplifier through the soldering portion.
As one of means for implementing high-density recording, a so-called combined separate type of magnetic head has recently been used in magnetic disk drives, which uses a magnetoresistive (MR) element that provides high reproduced output as a reproduction head and a thin-film head as a recording head. This type of head is called MR head.
The MR element in the MR head, while providing high reproduced output, has a drawback of being easy to suffer breakdown (electrostatic breakdown) due to electrostatic discharge (ESD). For this reason, a head amplifier circuit has also been developed recently which is equipped with a protection circuit for protecting the MR head from electrostatic breakdown due to ESD.
However, the provision of the MR protection circuit in the head amplifier does not always avoid the electrostatic breakdown of the MR head.
The inventors have found that the breakdown is easy to occur at the time of assembly work of incorporating the HSAs into the drive unit and that the breakdown is caused by ESD that occurs in the vicinity of the soldering portion of the relay FPC through a worker who is soldering together the relay FPC connected with the MR head and the main FPC on which the head amplifier is mounted. In such a case, the MR protection circuit, even if it is provided in the head amplifier circuit, does not function effectively against the ESD occurring in the vicinity of the soldering portion and the ESD directly affects the head. Thus, it is required to prevent effectively the MR head from suffering electrostatic breakdown due to ESD, particularly in the assembly process.
With increase in recording density, band limitation due to noise that occurs in interconnections between the head and the read amplifier and a degradation of the write characteristic due to inductance associated with interconnections between the head and the write driver circuit have become serious problems. It is required to solve these problems.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a head IC, a head amplifier circuit, a head suspension assembly, and a magnetic disk drive which are capable of avoiding electrostatic breakdown of a magnetic head due to, e.g., the occurrence of electrostatic discharge during the assembly process of incorporating the head suspension assembly into the magnetic disk drive.
It is another object of the present invention to provide a head IC, a head amplifier circuit, a head suspension assembly, and a magnetic disk drive which are capable of minimizing the noise leaped in the interconnections between a magnetic head and a read amplifier circuit.
It is still another object of the present invention to provide a head IC, a head amplifier circuit, a head suspension assembly, and a magnetic disk drive which are capable of solving the problem of a degradation of the write characteristic due to inductance associated with interconnections between a magnetic head and a write driver amplifier circuit to be solved.
According to an aspect of the present invention, there is provided a head suspension assembly comprising a magnetic head constituted by a magnetoresistive element for reading data and a head element for writing data; a slider for holding the magnetic head above a surface of a rotating magnetic recording medium; a suspension for supporting the slider; and a head integrated circuit mounted on the suspension, the head integrated circuit including a built-in protection circuit, electrically connected with the magnetoresistive element, for protecting the magnetoresistive element from electrostatic breakdown.
In the head suspension assembly, the head IC may include at least one of a read amplifier circuit for amplifying a read signal read by the magnetoresistive element from the magnetic recording medium and a write driver circuit for supplying the writing head element with a write current corresponding to a write data signal.
According to another aspect of the present invention, there is provided a head amplifier circuit for use in a magnetic disk drive including a head suspension assembly having a magnetic head constituted by a magnetoresistive element for reading data and a head element for writing data, a slider for holding the magnetic head above a surface of a rotating magnetic recording medium, and a suspension for supporting the slider, the head amplifier circuit comprising a head IC (Integrated Circuit) mounted on the suspension, the head IC including a built-in protection circuit, electrically connected with the magnetoresistive element, for protecting the magnetoresistive element from electrostatic breakdown; and a control IC for controlling the head IC.
In the head amplifier circuit, the head IC may include at least one of a read amplifier circuit for amplifying a read signal read by the magnetoresistive element from the magnetic recording medium and a write driver circuit for supplying the writing head element with a write current corresponding to a write data signal.
According to still another aspect of the present invention, there is provided a head IC (Integrated Circuit) for use in a magnetic disk drive including a head suspension assembly having a magnetic head constituted by a magnetoresistive element for reading data and a head element for writing data, a slider for holding the magnetic head above a surface of a rotating magnetic recording medium, and a suspension for supporting the slider, the head IC being mounted on the suspension, the head IC comprising first and second MR terminals connected to both ends of the magnetoresistive element; a bias current terminal connected to receive an externally supplied bias current; and a protection circuit, connected with the first and second MR terminals and the bias current terminal, for protecting the magnetoresistive element from electrostatic breakdown.
The head IC may further comprise a read amplifier circuit for amplifying a read signal read by the magnetoresistive element from the magnetic recording medium. The head IC may further comprise an adjust circuit, connected between the protec
Kaida Katsuhiko
Katsumata Makoto
Tsuruta Kenji
Faber Alan T.
Gary Cary Ware & Friedenrich LLP
Kabushiki Kaisha Toshiba
LandOfFree
Head IC, head amplifier circuit, head suspension assembly,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Head IC, head amplifier circuit, head suspension assembly,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Head IC, head amplifier circuit, head suspension assembly,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2894155