JPH0634347B2 - Head crash prevention disk device - Google Patents

Description

[Detailed Description of the Invention] In a magnetic disk device of a computer or the like, when the magnetic field becomes high in June, July, or August every year, that is, when the humidity is high, a head crash of a flying head occurs as shown in FIG. 1, which is 200 MB. Does not occur on discs of 300
It has been confirmed that this often occurs with disks of megabytes or more, the cause of this is unknown, and the manufacturer had difficulty in taking measures.

The ester in the magnetic coating formulation may combine with moisture in the air, that is, H ₂ O to form a white powdery substance, or the water combined with the ester may enter the pinhole of the disc and corrode the disc. is there. In addition to this, the present inventor has confirmed that, as the corrosion of the disc that requires special attention, filiform corrosion in which the disc surface bulges like a thread.

This filiform corrosion is a worm-like erosion of aluminum under the coating due to the combination of moisture in the air and intermolecular foreign substances or impurities such as silicon, calcium, potassium, copper, magnesium, etc. of the aluminum substrate of the disc. The present inventor confirmed that it was formed, and it is feared that this may raise the coating and cause head crush.

It was also confirmed by the present inventor that white spots (water spots or water spots and foreign matter) were generated on the disk in an environment of high humidity, and a head crash occurred at this portion. In addition, as a new proposal of the present invention,
It was discovered by the present inventor that moisture condensates on the surface of the head to change the aerodynamic shape of the head, resulting in a negative lift and causing a head crash.

The present invention is based on the above insight, and provides a device for preventing a head crash whose cause is unknown in the past.

These will be described with reference to the drawings. In a magnetic disk drive device, for example, as shown in FIG. 2, a spindle 2 is used to form a magnetic disk 1 having a magnetic layer formed on the surface of a disk-shaped aluminum substrate as a recording medium. A shaft is supported, and this is rotated at high speed from a motor 3 by a belt 4, and a magnetic head 7 is provided on an arm 6 which moves in and out in a radial direction of the disk 1 by a positioner 5. The magnetic head 7 is moved along the disk 1 to transfer data. Write or read, head 7
As shown in FIG. 3, the head 7 is supported by the suspension 10 by the air flow 9 generated by the high-speed rotation 8 of the disk 1, and the head 7 is flown at a very delicate height above the disk surface to write or read the record. But
At high humidity, the device is turned off at night, and in the early morning, the temperature of the head 7 drops below the dew point, and the moisture in the air condenses on the bottom surface of the head slider 11 to deposit water droplets. The surface shape of the lower surface changes so as to have a curved surface downward, and due to this aerodynamic shape change, a negative force for pressing down the head 7 is generated by the airflow 9, that is, the head 7 is pressed toward the disk 1 and the disk surface It was discovered by the present inventor that it collided with and caused a head crash.

This will be described in more detail. In FIG. 4, when the temperature of the head decreases in an environment of high humidity, dew drops 12 adhere to the lower surface of the head slider 11 and the lower surface of the head slider 11 forms a curved surface 13 downward. As shown in the figure, it shows a situation in which the changed air flow becomes 9 '.

The height H of the head 7 from the disk 1 is 0.8 to 0.9 micron for the 200 megabyte disk pack and 0.7 to 0.8 micron for the 300 megabyte disk pack, which is flying on the surface of the rotating disk but has 12 drops of water. Due to the attachment, the head slider has a length l ₁ of its upper surface and a length l of its lower surface.
₂ , the surface length l ₃ with water drops is l ₁ = l ₂ <l ₃
Since the lower surface l _{3 of} the head is longer than the upper surface l _1, the flow velocity of the lower surface of the head becomes faster due to Bernoulli's theorem, and the pressure drops, so that the head 7 is pressed against the disk 1 and collides with it, causing a head crash.

That is, if the angle of attack of the head 7 with respect to the disk 1 is α, the area is S, the density of the air flow 9 is ρ, the relative speed between the disk and the head is V, and the force for hitting the head with respect to the disk is -L. Therefore, the present inventor discovered that a head crash occurs at high humidity due to the above relationship.

FIG. 5 shows that when the adhered water is pushed to the rear part of the head slider by the rotating wind pressure of the disk or the angle of attack α of the head slider is large, the dew drop 12 on the head slider 11 shifts toward the trailing edge. 9 "shows the situation.

As shown in FIG. 6, when α is large, L is large, but when α is larger than the angle of attack α ₁ which is the maximum L _M , the present inventor has found that a stall condition occurs and lift L is lost to cause a head crash. It was

The present invention is an invention resulting from the investigation of the cause by the present inventor because a head crash whose cause is conventionally unknown occurs in high humidity. It is an epoch-making invention that eliminates these phenomena to prevent head crash. Yes, in a humid environment, etc.
This is a head crash prevention disk device that can be used after the condensation of (head disk interface) is removed.

An example of the embodiment of the present invention will be described below. FIG. 7 shows a disk pack type drive for writing or reading by contacting a rotating disk 1 with a magnetic head 7 ', and when the apparatus is stopped, the magnetic head 7'is In a magnetic disk device that stops at a position outside the disk 1 and becomes 7, a head 7 is located outside the disk, showing an embodiment of the present invention in which only the head 7 is heated and dried to remove water droplets 12. Sometimes a heater 14 is provided to heat the surface of the head,
Two heads 7 supported by an arm 6 are opposed to each other and heated, so that the dew condensation 12 is dried and removed before the heads enter the disk 1 and start flying.

After such warming up, the head 7 moves in the radial direction of the disk 1 by the positioner 5 of the actuator linear motor for writing or reading the data of the disk 1, and becomes the arm 6'and the head 7'and the heater. 14 powers off automatically.

FIG. 8 shows a case where the heater 14 shown in FIG.
This is an embodiment of the present invention in which the dry air heated by 16 is guided to the vicinity of the head by a thin pipe 17, and the tip nozzle 18 of the pipe 17 is sprayed onto the lower surface of the head slider 11 to remove condensation. After removing the dew condensation, dry air may be continuously sent by the device shown in FIG. 12 to prevent re-condensation.

The present invention can rapidly heat and dry two heads at the same time with a small amount of heat energy in a narrow space,
It can prevent head crashes that were unclear in the past, which occurred frequently in high humidity in disk drives, and prevent the destruction of disks, heads, drives, loss of data, etc., making a great contribution to the use and maintenance of computers. It is a very important invention that brings about.

In addition to the above example, various modifications can be considered in the embodiment of the means for removing the condensation of the HDI (head disk interface), but all of them are included in the present invention.

[Brief description of drawings]

1 is a side view of a magnetic disk drive device. FIG. 3 is a side view of a disk and a head. FIG. 4 is a side view of a disk and a head with dew droplets attached. FIG. 6 is a side view of the head on which the dew droplets are attached. FIG. 6 is a view showing the relationship between the angle of attack of the head with respect to the disk and the lift force of the head. FIG. 7 is a side view of the first embodiment of the present invention. Side view of the second embodiment of the invention 7, 7 '... Head 1 ... Disk 12 ... Condensation

Claims (1)

[Claims] 1. In a magnetic disk drive, wherein the magnetic head is in a stop position outside the disk when the apparatus is stopped, a heater for the head is provided outside the rotating disk, and the head is stopped when the head is stopped outside the disk. A head crush preventive disk device characterized in that the head is moved onto the disk surface after heating to remove dew.