Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
1999-11-10
2002-01-15
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
Reexamination Certificate
active
06339519
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a magnetic head device comprising a slider having a magnetic head, a resilient suspension structure carrying said slider and a head IC chip.
PRIOR ART
In conventional magnetic head device, a magnetic head for writing and/or reading magnetic information on a magnetic recording medium such as a magnetic disc is typically mounted on a slider which is maintained in a floating relationship with respect to the magnetic recording medium. The slider is supported by a suspension member formed by a resilient metallic film extended from an arm.
The head IC chip for amplifying a current for writing onto the magnetic head and a voltage for reading out from the magnetic head and for controlling the writing and/or reading operation is generally mounted on a movable arm provided for supporting one end of the suspension member. When the head IC chip is mounted on the movable arm, however, a lead wire connecting the head IC chip to the magnetic head is liable to be longer resulting in a cause of noise. In addition, a parasitic resistance and an inductance component generated by an increased length of the lead wire have an effect on increase of a rising and a falling times of pulse signals, which disturbs high speed data transfer. In order to solve the problems, there has been proposed by the Japanese Laid-Open Patent Publication No. Sho 53-69623 to mount the head IC chip on the slider. Further, in order to solve the similar problem, the Japanese Laid-Open Patent Publication No. Hei 3-108120 has also proposed to divide the IC chip into an IC main body and an IC sub-body and to mount the IC sub-body on the head slider.
In these known structure, though the noise problem caused by the long lead wire extended between the magnetic head and the head IC chip may be solved, there occur other problems that the temperature of the IC chip rises higher due to a heat generation of the IC chip itself caused by the current flowing therethrough during recording and that the magnetic head receives thermal effect of the heat generation of the IC chip.
More specifically, when the head IC is mounted on the movable arm, since said movable arm has a sufficient thermal capacity and an substantial area for heat dissipation, the temperature of the IC chip may be controlled to be sufficiently low owing to a thermal conduction through said movable arm and a heat dissipation from the arm surface. Further, since the IC chip is located far from the magnetic head, there is least possibility that the magnetic head is adversely affected by the heat generated in the head IC chip. To the contrary, when the head IC chip is located on the slider, it is difficult to ensure sufficient surface area for thermal diffusion so that it cannot be expected to lower the temperature through radiation of heat generated in the head IC chip. In addition, since the slider has a limited thermal capacity, it cannot be expected also to lower the temperature through the thermal conduction. As a result, the temperature of the head IC chip rises and thereby the reliability of the IC chip will be lowered. Further, since the magnetic head is located close to the head IC chip, there will be a possibility that the magnetic head is thermally affected by the heat generated in the IC chip and thereby the temperature of the magnetic head itself may rises up to an unacceptable level.
It is generally understood that the permissible temperature of a junction in the IC chip is 150° C. at the highest. This is because transistor junctions in the IC chip are gradually led to failure when they are operated for a long time under a temperature exceeding 150° C.
There is a request to apply more electric power to the head IC chip in order to obtain better recording current. This is because the reliability of medium has to be raised to make the density of magnetic record higher and consequently Hc value has to be made higher. Accordingly, much record current has to be applied to a record head to make large magnetic field for recording otherwise the recording is impossible. On the other hand, when the recording is performed in high frequency, more voltage is required to obtain fine waveform.
The applicant of the present invention has proposed in the Japanese Patent Application No. Hei 10-49105 the structure to improve radiation property by mounting the IC chip on the optimum position on the suspension. When the electric power consumption of the IC chip increases, however, some means is necessary to control the temperature of the IC chip to be lower than 150° C. which is a heat-resisting temperature thereof.
DISCLOSURE OF THE INVENTION
The present invention is accomplished in the light of the problems described above and the object thereof is to provides a magnetic head device in which a head IC chip may be located relatively closer to a magnetic head and a thermal effect may be controlled within a range of acceptable degree.
In order to accomplish above object, the present invention provides a magnetic head device comprising a head slider having a magnetic head thereon, a suspension member which is made of thin resilient material and supports said head slider at one end thereof, and a head IC chip, said suspension member being attached to other member at the other end thereof, wherein said head IC chip is mounted on said suspension member.
The inventor of the present invention found that, in the structure of the magnetic head device described above in which the head slider having the magnetic head thereon is mounted on an end of the suspension member formed by thin resilient material, when the head IC chip is mounted on the suspension member, depending on a surface area of the head IC chip, thermal conduction and heat dissipation may not be sufficient and the temperature of the IC chip may rise up beyond the permissible level and the magnetic head also may be subject to thermal effect. He found also that, when a disc side area thereof is selected to be appropriate value, the temperature of the IC chip may be held within the acceptable range and that of the magnetic head may also be held to be lower.
In an aspect of the present invention, the head IC chip is mounted on a surface of the suspension member at a side facing to the disc, a weight thereof is equal to or less than 1 mg, and a disc side area thereof is equal to or more than 0.6 mm
2
. In another aspect of the present invention, an electric power consumption of the head IC chip is equal to or less than 410 mW and the disc side area thereof is equal to or more than 1.1 mm
2
. In still another aspect of the present invention, the head IC chip is mounted on the surface of the suspension member at a side facing to the disc at a point where a relative linear velocity equal to or more than 15 m/sec is generated with respect to said disc at the outermost periphery thereof, and the electric power consumption of the head IC chip is equal to or less than 410 mW, and the disc side area thereof is equal to or more than 0.9 mm
2
. In yet another aspect of the present invention, the head IC chip has a weight equal to or less than 1 mg, the electric power consumption thereof is equal to or less than 250 mW, and the disc side area thereof is equal to or more than 0.6 mm
2
. When the electric power consumption of the head IC chip is equal to or less than 560 mW, the temperature of the head IC chip may be controlled to be equal to or lower than 150° C. by making the disc side area thereof be equal to or more than 1.4 mm
2
. In this case, when the head IC chip is mounted on the point where a relative linear velocity equal to or more than 25 m/sec is generated with respect to said disc, the disc side area may be made to be equal to or more than 1.3 mm
2
.
When the disc side area is less than the range described above, the temperature of the head IC chip rises up beyond the permissible level. As a reason thereof, it is estimated that there is a limit to use the suspension member as a radiation plate and the cooling of the IC chip is insufficient. As the mounting point of the IC chip
Kawai Mitsuyoshi
Morita Haruyuki
Nomura Izumi
Shiraishi Masashi
Wada Takeshi
Frishauf, Holtz Goodman, Langer & Chick, P.C.
TDK Corporation
Tupper Robert S.
LandOfFree
Magnetic head device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic head device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic head device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2849645