1. Field of the Invention
The present invention relates to a method for controlling the operation of a hard disk drive device based upon a detected value of surrounding atmospheric pressure and a hard disk drive device capable of controlling its operation based upon the detected value of the atmospheric pressure.
2. Description of Related Art
At least one magnetic recording disk is contained in a hard disk drive device, and the data is stored on both surfaces of the magnetic recording disk. One read/write head is provided on each recording surface. In one example, four read/write heads are used with two recording disks; each read/write head is mounted on a front end of a head support arm, and rear ends of four head support arms are so connected to each other that all the read/write heads address the same radial cylinder positions on each of the four recording surfaces of the two recording disks. In this manner, all the read/write heads address the same radial positions of the four recording surfaces which define a cylinder, and as such the radial cylinder positions are called cylinder position.
A prior hard disk drive device used a contact start/stop scheme in which a head/slider assembly is landed on a rest region or a non-recording region located inside the inner most recording cylinder of a magnetic recording disk during a power off period, and takes off from the surface of the rest region when the magnetic recording disk is rotated. To realize a reliable take off, the surface of the disk must be roughened. The reasons for forming the roughness on the recording surface is that if the surface is made smooth, the head/slider assembly sticks to the recording surface due to interatomic forces, thereby preventing take off.
As the diameter of the magnetic recording disk becomes smaller, many efforts have been made to increase the recording density and to improve S/N ratio.
To increase the recording density and to improve S/N ratio, a flying height of the head/slider assembly, i.e., a space between the head/slider assembly and the recording surface of the disk has been decreased. In the magnetic recording disk, it was difficult to decrease the height of the head/slider assembly over the roughened recording surface, since the head/slider assembly tended to contact to top portion of the roughened surface.
A hard disk drive device has been developed which uses a load/unload scheme in which a ramp element 2 is mounted at the peripheral of the magnetic recording disk 1, as shown in the FIGS. 1(A) and 1(B). The surface of the ramp element 2 is ramped, and a front end 3 of a head support arm 4 rides on the ramped surface of the part 2, and moves in the direction of an arrow 6 to the rest position of the ramp element 2, as shown in FIG. 1(B), when the head support arm 4 is rotated around a pivot point 5 in the clockwise direction in FIG. 1(A). When the read/write operation is started, the magnetic recording disk 1 is rotated by a motor, not shown, and the head support arm 4 is moved from the rest position in a direction of an arrow 8, and is moved to a flying position above the desired cylinder of the magnetic recording disk 1 to read the data from the cylinder or write the data into the cylinder.
The rotational speed, i.e., the revolution per minute (RPM), of the magnetic recording disk 1 is so designed to generate an air bearing with an appropriate pressure which causes the head/slider assembly 7 of the head support arm 4 to fly above the surface of the magnetic recording disk 1.
In this manner, the head/slider assembly 7 does not land on the surface of the disk 1, so that the surface of the disk 1 can be polished to remove the roughness of the surface of the disk used in the contact start/stop scheme, and the flying height of the head/slider arm 4 in the read/write mode and an error recovery mode can be reduced in comparison with the flying height of the contact start/stop scheme.
Describing the flying height of the head/slider assembly 7 in the read/write mode and the error recovery mode with reference to FIG. 2, in the read/write mode, the flying height of the head/slider assembly 7 is maintained at the height H1 by maintaining the first rotation speed. If the hard disk drive device senses a read error or a write error, the hard disk drive device enters the error recovery mode by reducing the rotational speed of the disk 1 to a second rotational speed which is lower than the first rotational speed to maintain the height H2. This height H2 is so selected to bring the lower surface of the head/slider assembly 7 close to the surface of the disk 1 to wipe off any dusts or residual material on the surface of the magnetic recording disk 1.
The problem found by the inventors of the present invention is that the head/slider assembly 7 tends to stick to the surface of the magnetic recording disk 1 when the hard disk drive device enters the error recovery mode while the hard disk drive device is used in an airplane flying at a high altitude.