JPS6226686A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To keep the state of low humidity in a tightly closed housing constant by providing two sets of desiccant cases, air holes having fixed flow passage resistance, and air filters in the housing. CONSTITUTION:The device is provided with two cases 6, 6' of desiccant, an air hole 7 having flow passage resistance corresponding the size of less than 1mm in diameter and less than 1mm in length provided in one of the desiccant cases, an air hole 7' having flow passage resistance corresponding to less than 0.01 times flow passage resistance provided in another desiccant case and air filters 8, 8' sealed on each of air holes in a tightly closed housing 3. Thereby, the state of low humidity in the housing can be kept constant for a long period even against abrupt environmental change.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk drive, and more particularly to a magnetic disk drive having an internal dehumidifying structure.

[Prior Art] Generally, as the performance of magnetic disk devices increases, it is becoming necessary to not only clean the air inside the device but also maintain low humidity.

For this reason, an example of a magnetic disk device has a structure in which the housing that houses the AI disk and the magnetic head has improved sealing performance, has micro holes as pressure adjustment holes for the inside and outside air, and is further equipped with a desiccant inside the housing. be. Conventionally, in this type of magnetic disk drive, the desiccant case filled with desiccant is
Considering the lifespan of the desiccant, only micropores are provided as ventilation holes.

[Problems to be Solved] The conventional magnetic disk drive described above is less susceptible to sudden changes in the environment due to the micro holes provided in the housing, and furthermore, the micro holes provided in the desiccant case are Significantly extends the life of the desiccant. However, if, for example, the environmental temperature suddenly drops, the air within the housing will be cooled and its relative humidity will rise sharply. A desiccant generally exhibits a dehumidifying effect in equilibrium with the relative humidity, but if the vents in the desiccant case are minute holes, it will take an extremely long time to achieve equilibrium. In other words, when the relative humidity inside the housing suddenly changes, the desiccant takes effect and the time constant until the inside of the housing reaches equilibrium at low humidity is extremely long.

[Means for Solving Problems] The present invention has been made by focusing on the above-mentioned conventional problems, and provides a magnetic disk that can maintain a constant low humidity state in a sealed housing for a long period of time even in the face of rapid environmental changes. The aim is to provide the equipment.

To this end, the present invention provides a magnetic disk drive in which a magnetic disk and a magnetic head are housed in an airtight housing having minute holes, which includes two dryer sub-cases each containing a desiccant, and one of the desiccant cases. diameter 1m
m or less, a length of 1 m, a vent hole having a flow path resistance equivalent to a size of m or less, and a flow path resistance equivalent to 0.01 times or less of the flow path resistance provided on the other side of the desiccant case. The present invention provides a magnetic disk drive characterized in that the inside of a sealed housing includes a vent hole having a diameter of 10 mm, and an air filter sealed and affixed to each of the vent holes.

[Example] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a magnetic disk device according to an embodiment of the present invention.

The magnetic disks 1 are stacked on a rotating mechanism section, and a magnetic head 2 is mounted on the drive section facing the magnetic disks 1, and is housed in a housing 3 consisting of a base plate and a cover. A part of the housing 3 has micro holes 4.
is installed to adjust the pressure with the outside air. Further, inside the housing 3, a desiccant case 6.6' containing a desiccant 5.5' is installed with its ventilation hole 7.7' facing a position communicating with the air inside the housing.
are micropores with an opening area of 1 mm or less in diameter, and the opening of the other vent hole 7' is much larger than that of the vent hole 7. Air filter 8.8' is installed in the inner ventilation hole 7.7'.
are affixed to each of them to prevent dust generated by the desiccant 5 and 5' from contaminating the inside of the housing 3. Since the opening areas of the ventilation hole 7 and the ventilation hole 7' are extremely different, the dehumidifying function is shared between them. That is, the ventilation holes 7, which are microscopic holes, have a slow dehumidification effect to sufficiently maintain the life of the desiccant 5, while the ventilation holes 7', which have a large opening area,
The dehumidifying effect is achieved in response to sudden changes in relative humidity within the housing. In the long term, the desiccant 5' also maintains a lifespan substantially equal to that of the desiccant 5 by trying to maintain an equilibrium relationship between the desiccant 5 and the relative humidity within the housing 3.

Incidentally, the relationship between the flow path resistance of the vent and the time constant can be briefly described from a quantitative viewpoint as follows. Channel resistance is inversely proportional to the area of the channel and proportional to its length. The equilibrium of relative humidity through the vent can be understood as a water vapor diffusion phenomenon, and the time constant until this equilibrium is reached is proportional to the flow path resistance of the arrow.

Therefore, in the case of the aforementioned flow path resistance of 1 mm or less in diameter and 1 mm or less in length, the time constant for water vapor diffusion is a value of several tens of millimeters, whereas in the case of a flow path resistance of 0.01 times that value, the time constant is Get the value for several hours.

[Effects of the Invention] As described above, the present invention provides a magnetic disk device that stores a magnetic disk and a magnetic head in a sealed housing having micropores, which includes two desiccant cases each containing a desiccant, and a A ventilation hole having a flow path resistance corresponding to a size of 1 mm or less in diameter and 1 mm or less in length provided on one side of the desiccant case, and 0.01 times the flow path resistance provided on the other side of the desiccant case. Since the magnetic disk device is characterized in that the inside of a sealed housing is equipped with a ventilation hole having a flow path resistance corresponding to the following, and an air filter affixed to each of the ventilation holes,
By providing dehumidification functions in multiple locations and making large differences in the time constants until each dehumidifying effect appears, it is possible to maintain a constant low humidity state within the housing over a long period of time even in the face of sudden environmental changes. There is.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magnetic disk device according to an embodiment of the present invention. 1: Magnetic disk 2: Magnetic head 3: Housing 4: Microhole 5.5': Desiccant 6.6': Desiccant case 7.7' 2 Vent holes 8.8': Air filter

Claims (1)

[Claims] In a magnetic disk device in which a magnetic disk and a magnetic head are housed in a sealed housing having minute holes, there are two desiccant cases each containing a desiccant, and a desiccant case with a diameter of 1 mm or less and a length provided in one of the desiccant cases. A vent hole having a flow path resistance corresponding to a size of 1 mm or less and a flow path resistance of 0.01 mm provided on the other side of the desiccant case.
1. A magnetic disk drive comprising, inside a sealed housing, a vent hole having a flow path resistance equal to or less than twice that of the vent hole, and an air filter sealed and affixed to each of the vent holes.