U.S. patent application number 11/819551 was filed with the patent office on 2008-01-17 for hard disk drive for vehicle.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Ken Nishioka.
Application Number | 20080011641 11/819551 |
Document ID | / |
Family ID | 38948157 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080011641 |
Kind Code |
A1 |
Nishioka; Ken |
January 17, 2008 |
Hard disk drive for vehicle
Abstract
A hard disk drive, which is mounted on a vehicle, includes a
casing, a hard disk, a magnetic head, and a sealing device. The
casing has a breathing hole. The hard disk is assembled in the
casing. The magnetic head is assembled in the casing. The sealing
device seals the breathing hole of the casing in accordance with
external atmospheric pressure.
Inventors: |
Nishioka; Ken;
(Toyoake-city, JP) |
Correspondence
Address: |
POSZ LAW GROUP, PLC
12040 SOUTH LAKES DRIVE, SUITE 101
RESTON
VA
20191
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
38948157 |
Appl. No.: |
11/819551 |
Filed: |
June 28, 2007 |
Current U.S.
Class: |
206/722 ;
G9B/25.003; G9B/33.045; G9B/33.048 |
Current CPC
Class: |
G11B 33/1486 20130101;
G11B 25/043 20130101; G11B 33/1466 20130101 |
Class at
Publication: |
206/722 |
International
Class: |
B65D 85/00 20060101
B65D085/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 14, 2006 |
JP |
JP 2006-194202 |
Claims
1. A hard disk drive, which is mounted on a vehicle, comprising: a
casing that has a breathing hole; a hard disk that is assembled in
the casing; a magnetic head that is assembled in the casing; and a
sealing device that seals the breathing hole of the casing in
accordance with external atmospheric pressure.
2. The hard disk drive according to claim 1, wherein: the sealing
device includes a diaphragm member provided inside the breathing
hole; and the diaphragm member is resiliently bent and deformed to
seal the breathing hole when the external atmospheric pressure is
reduced to be equal to or less than a predetermined value.
3. The hard disk drive according to claim 1, wherein: the sealing
device includes a bag member provided inside the breathing hole;
the bag member is made of a soft material and has gas filled inside
the bag member, and the bag member is inflated and deformed in
accordance with a decrease of the external atmospheric pressure to
seal the breathing hole.
4. The hard disk drive according to claim 3, further comprising: a
detecting device that detects an elevation of a position of the
vehicle or the external atmospheric pressure of the vehicle; and a
heating device that heats the bag member to forcibly inflate and
deform the bag member when the detecting device detects the
elevation, which is equal to or higher than a threshold value, or
when the detecting device detects the external atmospheric
pressure, which is equal to or less than a threshold value.
5. The hard disk drive according to claim 1, wherein the sealing
device includes a cover member for opening and sealing the
breathing hole, the hard disk drive further comprising: a detecting
device that detects an elevation of a position of the vehicle or
the external atmospheric pressure of the vehicle; and an actuating
device that actuates the cover member to seal the breathing hole
when the detecting device detects the elevation, which is equal to
or higher than a threshold value, or when the detecting device
detects the external atmospheric pressure, which is equal to or
less than a threshold value.
6. The hard disk drive according to claim 4, wherein: the detecting
device includes a vehicle position detecting device that detects a
position of the vehicle; and the detecting device detects the
elevation of the position of the vehicle based on the position of
the vehicle detected by the vehicle position detecting device.
7. The hard disk drive according to claim 5, wherein: the detecting
device includes a vehicle position detecting device that detects a
position of the vehicle; and the detecting device detects the
elevation of the position of the vehicle based on the position of
the vehicle detected by the vehicle position detecting device.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2006-194202 filed on Jul.
14, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a hard disk drive for a
vehicle, which is equipped on the vehicle, such as a car, and which
stores, for example, geographic data (map data) for navigation or
music data.
[0004] 2. Description of Related Art
[0005] For example, a car navigation system carries a hard disk
drive (HDD), which can store large data, as storage means for
storing the geographic data. Also, the hard disk drive stores music
data to enjoy with a car audio system.
[0006] Generally, this kind of hard disk drive includes a hard
disk, a motor, an arm, and another motor, which are all assembled
in a casing of a thin rectangle box shape. The motor rotates the
hard disk at high speed. The arm has a magnetic head at an end. The
another motor drives the arm. At the time of reading and writing of
data, the magnetic head is provided to float on the face of the
hard disk rotated at high speed with a very small clearance between
the magnetic head and the face of the hard disk.
[0007] Note that the casing is adapted to be sealed for limiting
dust and moisture from entering inside the casing. However, a small
breathing hole, which communicates with exterior, is formed in one
place of the casing for limiting the casing from being broken due
to atmospheric pressure difference between the inside and outside
of the casing, for example, when the hard disk drive is carried by
the aircraft. The breathing hole is provided also for limiting the
internal pressure of the casing from changing (increasing) due to
the temperature change by the heat generated during use of the hard
disk drive. Note that a filter, which is filled with moisture
absorbent, is installed in the internal side of this breathing
hole.
[0008] Such a hard disk drive is assembled in an apparatus, such as
a personal computer used in home and office. Therefore,
conventionally, the atmospheric pressure is not particularly
considered. However, in a case, where the hard disk drive is
assembled in a car navigation system as above, when the vehicle
runs at an area of a high elevation (altitude), such as the
mountainous area, an appropriate clearance may not be formed
between the face of the hard disk and the magnetic head during the
operation of the hard disk because the atmospheric pressure is low.
This means that the flying height of the magnetic head becomes low,
and the reading and writing may not be performed normally. In a
worse case, the magnetic head may come into contact with the hard
disk, and breakage (so-called crash) may occur.
[0009] Thus, art, which deals with the above disadvantage, is
disclosed in Japanese Patent Laid-Open No. 2004-355722 bulletin. In
the art disclosed by Japanese Patent Laid-Open No. 2004-355722
bulletin, when, an imaging apparatus is used with an airplane, the
altitude of the spot is known based on the position information
detected by a GPS. Also, depending on the detected altitude, the
access to the hard disk is limited. Also, in a navigation apparatus
using a hard disk drive disclosed in Japanese Patent Laid-Open No.
2004-317385 bulletin, a geographic data (map data) prestored in a
hard disk is made to be stored in a backup memory in accordance
with the position information from a GPS receiver or detection of
the atmospheric pressure sensor. When altitude (atmospheric
pressure) of the vehicle exceeds its threshold value, the access to
the hard disk is limited, and a geographic data is read from the
backup memory to be displayed.
[0010] By the both arts described in the above Japanese Patent
Laid-Open No. 2004-355722 bulletin, and Japanese Patent Laid-Open
No. 2004-317385 bulletin, when the altitude (atmospheric pressure)
exceeds the threshold value, the access to hard disk is limited.
However, while the hard disk cannot be accessed, it is necessary to
read data from an additional storage unit, such as a memory.
Because of this, an additional hardware structure, such as the
memory, is necessary. Also, the unnecessary process, such as the
writing to the additional storage unit, is disadvantageously
required.
SUMMARY OF THE INVENTION
[0011] The present invention is made in view of the above
disadvantages. Thus, it is an objective of the present invention to
address at least one of the above disadvantages.
[0012] To achieve the objective of the present invention, there is
provided a hard disk drive, which is mounted on a vehicle and
includes a casing, a hard disk, a magnetic head, and a sealing
device. The casing has a breathing hole. The hard disk is assembled
in the casing. The magnetic head is assembled in the casing. The
sealing device seals the breathing hole of the casing in accordance
with external atmospheric pressure.
BRIEF DESCRIPTION OF DRAWINGS
[0013] The invention, together with additional objectives, features
and advantages thereof, will be best understood from the following
description, the appended claims and the accompanying drawings in
which:
[0014] FIG. 1A is an enlarged longitudinal sectional view of a main
portion showing a condition, where a breathing hole is opened,
according to a first embodiment of the present invention;
[0015] FIG. 1B is an enlarged longitudinal sectional view of the
main portion showing a condition, where the breathing hole is
sealed, according to the first embodiment of the present
invention;
[0016] FIG. 2 is a perspective view of a hard disk drive in a
condition, where a top cover of the hard disk drive is removed;
[0017] FIG. 3 is a perspective view showing a filter member of a
rear of the top cover;
[0018] FIG. 4 is a block diagram schematically illustrating an
electric structure of a car navigation system;
[0019] FIG. 5A is an enlarged longitudinal sectional view of a main
portion showing a condition, where a breathing hole is opened,
according to a second embodiment of the present invention;
[0020] FIG. 5B is an enlarged longitudinal sectional view of the
main portion showing a condition, where the breathing hole is
sealed, according to the second embodiment of the present
invention;
[0021] FIG. 6A is an enlarged longitudinal sectional view of a main
portion showing a condition, where a breathing hole is opened,
according to a third embodiment of the present invention; and
[0022] FIG. 6B is an enlarged longitudinal sectional view of the
main portion showing a condition, where the breathing hole is
sealed, according to the third embodiment of the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First Embodiment
[0023] The first embodiment, in which the present invention is
applied to a hard disk drive assembled in a car navigation system
(vehicle navigation system), is explained referring to FIGS. 1A to
4. At first, FIG. 4 diagrammatically illustrates an electric
structure of a car navigation system 1 carried by a vehicle
(automobile). A general structure of this car navigation system 1
is simply described.
[0024] The car navigation system 1 includes a navigation control
circuit 2 and connected equipments connected to the control circuit
2. The connected equipments include a GPS receiver 3, a gyrosensor
4, an acceleration sensor 5, a vehicle speed sensor 6, a remote
control sensor 7, an operation switch group 8, a modem 9, an
external information input/output device 10, a display device 11,
and a hard disk drive (HDD) 12, which relates to the present
embodiment. The navigation control circuit 2 mainly includes a
microcomputer (CPU) and controls a whole system. Also, the modem 9
is connected to a cellular phone 13 (or, an automobile telephone),
and is adapted to perform radio communication with an information
delivery center 14.
[0025] The GPS receiver 3, the gyrosensor 4, the acceleration
sensor 5, and the vehicle speed sensor 6 function as a vehicle
position detecting device for detecting a position of the vehicle.
The control circuit 2 is adapted to calculate a current position
(longitude, latitude, altitude) of the own vehicle with high
accuracy based on the signals outputted from the above sensors. In
other words, the control circuit 2, the GPS receiver 3, the
gyrosensor 4, the acceleration sensor 5, and the vehicle speed
sensor 6 constitute a detecting device that detects an elevation of
a position of the vehicle or the external atmospheric pressure of
the vehicle. The operation switch group 8 has a structure such that
a user performs various operating instruction to the switch group
8. The operation switch group 8 includes a mechanical switch, which
is installed in the vicinity of the display device 11, and a touch
sensitive panel provided at a surface of the display device 11. For
example, the display device 11 has a full color liquid crystal
display, and displays a navigational view (a geographical map
display view) or various messages.
[0026] And the hard disk drive 12 (hard disk) stores a geographic
data (map data), various programs executing navigation function,
contents, a user data, and the like. For example, the geographic
data includes the road map data of the Japanese whole land and
facilities data to accompany it. Also, the geographic data includes
data to regenerate a road map on a screen of the display device 11.
The control circuit 2 performs navigation function, such as a
location function or a root guidance function, using structure of
the software. By the location function, a current position (and,
direction of traveling) of the own vehicle is superposed with a
road map to be displayed in the display device 11. The root
guidance function automatically calculates a recommended travel
path to a destination assigned by a user, and guides the path.
[0027] A structure of the hard disk drive 12 according to the
present embodiment is explained in detail below referring to FIGS.
1A to 3. The hard disk drive 12 has a hard disk 16 (platter), a
spindle motor 17, a magnetic head 18, an arm 19, a voice coil motor
20, and a controller, which are all assembled in a metal casing 15
of a thin rectangular box shape as shown in FIG. 2. The spindle
motor 17 rotates the hard disk 16 at high speed. The magnetic head
18 reads and writes data in the hard disk 16. The arm 19 drives the
magnetic head 18. The voice coil motor 20 moves the arm 19
[0028] The casing 15 includes a base 15a and a top cover 15b, which
are located to seal the top face of the base 15a. A connector
portion 21 for external connection (e.g., connection with the
control circuit 2) is provided in the front end face of the base
15a. A breathing hole 22 is formed in one place (around a central
front part) of the top cover 15b as shown in FIG. 1. The breathing
hole 22 serves to equalize internal pressure in the casing 15 with
external atmospheric pressure to limit pressure differential from
occurring.
[0029] Also, as shown in FIGS. 1A, 1B, and 3, a filter member 23 is
provided in a circular-arc-shaped region, Which includes the
breathing hole 22, on the rear side (underside) of the top cover
15b. The filter member 23 includes a moisture absorbent, for
example, activated carbon such that dust and moisture are limited
from entering into the casing 15.
[0030] As shown in FIG. 1, a diaphragm member 24 is provided inside
the breathing hole 22 of the casing 15 (inner face side of the top
cover 15b) in the present embodiment. The diaphragm member 24
functions as a sealing device for sealing the breathing hole 22
depending on external atmospheric pressure. The diaphragm member 24
is made of a material, for example, a rubber, a plastic, and metal,
to have a discoid shape, which is bendable to be deformed. In this
case, a cavity 23a, at which the filter member 23 does not exist,
is made inside the breathing hole 22. The diaphragm member 24 is
provided at the cavity 23a (a position slightly spaced-apart from
an inner face (under face) of the top cover 15b) with an outer
peripheral edge of the diaphragm member 24 supported. Typically,
there is formed a very small hole (clearance) at a boundary between
the outer peripheral edge of the diaphragm member 24 and the
breathing hole 22 of the casing 15. The small hole (clearance)
restricts air flow out of or into the casing 15, and the small hole
(clearance) has a size such that the diaphragm member 24 is bent
and deformed due to a differential pressure between the inside and
outside of the casing 15.
[0031] The diaphragm member 24 becomes to have a curved shape
projecting downward as shown in FIG. 1A to open the breathing hole
22 in a normal state (e.g., a pressure applied on a top face side
of the diaphragm member 24 of greater than 0.7 atm). In contrast,
as shown in FIG. 1B, the diaphragm member 24 is bent elastically
(resiliently) to be deformed to project upwardly when external
atmospheric pressure falls to a predetermined value (e.g., when a
pressure applied on the top face side of the diaphragm member 24
becomes equal to or less than 0.7 atm). Therefore, the diaphragm
member 24 tightly contacts with an inner face of the top cover 15b
(a perimeter portion of the breathing hole 22) to seal the
breathing hole 22. When external atmospheric pressure is returned
to an original pressure (e.g., the above pressure applied to the
top face side being of greater than 0.7 atm), the diaphragm member
24 returns to an original state (e.g., the above normal state).
[0032] The action of the above structure is described below. The
hard disk drive 12 according to the present embodiment is assembled
in the vehicle (automobile) as part of the car navigation system 1.
When vehicle runs on a level ground with a comparatively high
atmospheric pressure (around 1 atm), such as on a lowland area, the
diaphragm member 24 has the curved shape projecting downward as
shown in FIG. 1A to open the breathing hole 22 formed at the casing
15. Thus, air flows out of or into the casing 15 through the
breathing hole 22 when difference is generated between external
atmospheric pressure and atmospheric pressure in casing 15. As a
result, pressure differential between the interior and the exterior
of the casing 15 is canceled.
[0033] In contrast, when the vehicle runs in an area of high
elevation (altitude) (e.g., an altitude of equal to or more than
3,000 m), such as the mountains ground, atmospheric pressure
becomes low (for example, equal to or less than 0.7 atm). Due to
this, when the hard disk drive 12 were operated in a comparative
example state, where the external atmospheric pressure were equal
to the internal atmospheric pressure in the casing 15, an
appropriate clearance might not be formed between the face of the
hard disk 16 and the magnetic head 18. As a result of this, a
flying height of the magnetic head 18 might go lower, and the
reading and writing might not be performed normally. In a worse
case, the magnetic head 18 might disadvantageously come into
contact with the hard disk 16 to cause breakage (so-called
crash).
[0034] However, unlike the above comparative example state, the
diaphragm member 24 is provided in the inside of the breathing hole
22 in the present embodiment. Therefore, the diaphragm member 24 is
bent to be deformed as shown in FIG. 1B to seal the breathing hole
22 when external atmospheric pressure is reduced to be equal to or
less than the predetermined value (when a pressure applied to the
top face side of the diaphragm member 24 becomes equal to or less
than, for example, 0.7 atm). Pressure in the casing 15 can be kept
at constant (pressure of greater than 0.7 atm) due to this without
being influenced by the external atmospheric pressure because the
outflow (inflow) of air through the breathing hole 22 is
limited.
[0035] In other words, for example, the pressure differential
between the interior and the exterior of the casing 15 during the
carriage of the hard disk drive 12 by an air plane is limited from
occurring. Also, the internal pressure in the casing 15 is limited
from changing (increasing) due to heat generation of components
during use.
[0036] As a result of this, even if the external atmospheric
pressure lowers (i.e., the hard disk drive 12 is used in a position
of a high elevation), pressure in the casing 15 does not go low
accordingly. Therefore, the appropriate clearance between the face
of the hard disk 16 and the magnetic head 18 can be formed (kept)
such that access to the hard disk 16 is enabled. In other words, in
the area of high elevation, the hard disk drive 12 can be used
similarly to a normal state (a lowland area). Note that the
diaphragm member 24, so to speak, is automatically deformed to come
back to the state shown in FIG. 1A to open the breathing hole 22
when the external atmospheric pressure returns to the original
pressure.
[0037] Thus, the hard disk drive 12 of the present embodiment
includes the diaphragm member 24 such that the breathing hole 22
formed to the casing 15 is, so to speak, automatically sealed
(blocked up) when the external atmospheric pressure falls to be
equal to or less than the predetermined value. Thus, the hard disk
drive 12 of the present embodiment differs from the conventional
hard disk drive, in which access to the hard disk, when used in the
high elevation area (the area of low atmospheric pressure), is
prohibited. When the hard disk drive 12 of the present embodiment
is used in the high elevation area, the appropriate clearance
between the face of the hard disk 16 and the magnetic head 18 can
be ensured (be reliably formed). Therefore, while preventing damage
of the hard disk 16, the access to the hard disk 16 can be
enabled.
[0038] In this case, the conventional additional back-up memory is
not required. Also, the sealing device has a mechanical structure.
Therefore, the hard disk drive 12 has simple structure, and also is
made inexpensively. In the present embodiment, the sealing device
includes the diaphragm member 24, which is bent elastically
(resiliently) to be deformed (displaced) to seal (block up) the
breathing hole 22 when the external atmospheric pressure becomes
equal to or less than the predetermined value. Therefore, the
breathing hole 22 is, so to speak, automatically sealed when the
external atmospheric pressure falls to be equal to or less than the
predetermined value. Also, the breathing hole 22 is adapted to be
automatically opened when the external atmospheric pressure returns
to the original pressure. The present embodiment of enables the
above structure by a simple construction inexpensively.
Second Embodiment
[0039] FIG. 5 shows the second embodiment of the present invention.
FIG. 6 shows the third embodiment of the present invention. Note
that, in the second embodiment, the present invention is also
applied to a hard disk drive, which is assembled in a car
navigation system, and which stores geographic data. The structure
of a sealing device for sealing (blocking up) the breathing hole 22
in the second embodiment is different from that in the first
embodiment. Thus, similar components similar to those in the first
embodiment are indicated by the same numerals. New illustration and
detailed description of the similar components are omitted so that
only different points are described below.
[0040] In the second embodiment shown in FIG. 5, a bag member 31,
which serves as a sealing device for sealing the breathing hole 22
in accordance with external atmospheric pressure, is installed
(provided) in the cavity 23a of the filter member 23 inside the
breathing hole 22 of the casing 15 (the inner face side of the top
cover 15b). For example, the bag member 31 is made of a material,
such as a plastic film or a rubber. The bag member 31 is formed to
have a thin circular bag shape, and is adapted to be inflatable and
returnable to its original shape after inflation deformation. Gas
(e.g., air) with a pressure of, for example, 1 atm is filled inside
the bag member 31, and the bag member 31 is tightly sealed.
[0041] Further still, in the present embodiment, a heat generating
element 32 to heat the bag member 31 (e.g., to heat air inside) is
provided at an under face side of the bag member 31 (e.g., is
provided on an opposite side of the bag member 31 opposite the
exterior). The heat generating element 32 generates heat by
energization, and functions as a heating device. When the
navigation control circuit 2 detects that an elevation (altitude)
of a position of the vehicle (own vehicle position) is equal to or
more than a threshold value (e.g., 3,000 m) based on a signal from,
such as GPS receiver 3, the navigation control circuit 2 outputs to
the hard disk drive 12 an energization command signal for
energizing the heat generating element 32. When the elevation of
the own vehicle position becomes equal to or less than the
threshold value afterwards, the navigation control circuit 2 is
adapted to output to the hard disk drive 12 a deenergization
command signal for deenergizing the heat generating element 32. The
controller in the hard disk drive 12 is adapted to control the
energization and deenergization of the heat generating element 32
based on these received energization command signal and
deenergization command signal.
[0042] Due to this, the bag member 31 is of a normal size (a
relatively shrank state) as shown in FIG. 5A in a normal state. The
normal state is, in other words, a state, where the elevation of
the own vehicle position has not reached the threshold value
(external atmospheric pressure is around 1 atm) and also the heat
generating element 32 has not heated the bag member 31. At this
time, the top face of the bag member 31 is positioned apart from
the inner face of the top cover 15b downwardly, and the breathing
hole 22 is opened.
[0043] In contrast, when the elevation of the own vehicle position
becomes equal to or more than the threshold value (e.g., 3,000 m),
the bag member 31 is heated by the heat generating element 32. At
the same time, the external atmospheric pressure greatly falls
relative to the internal pressure (e.g., equal to or less than 0.7
atmospheric pressure), and therefore, as shown in FIG. 5B, the bag
member 31 is inflated and deformed upwardly. The top face part of
the bag member 31 tightly contacts with the inner face of the top
cover 15b (the peripheral portion of the breathing hole 22) to seal
the breathing hole 22. Note that the bag member 31 gradually comes
back to the original position and to a state shown in FIG. 5A when
the elevation of the own vehicle decreases, and the heat generating
element 32 is deenergized.
[0044] In the above second embodiment, the bag member 31 serving as
the sealing device and the heat generating element 32 serving as
the heating device are provided to the hard disk drive 12. As thus
described, similar to the first embodiment, when the hard disk
drive 12 is used in a high elevation area, the appropriate
clearance between the face of the hard disk 16 and the magnetic
head 18 can be ensured. Therefore, while damage of the hard disk 16
is limited, the access to the hard disk 16 can be enabled.
[0045] In the present embodiment, in particular, gas in the bag
member 31 is heated by the heat generating element 32 when the
elevation of the own vehicle position is detected to be equal to or
higher than the threshold value. Then, the bag member 31 is, so to
speak, forcibly inflated to be deformed such that the breathing
hole 22 is sealed. As a result, when the external atmospheric
pressure lowers, the breathing hole 22 can be sealed surely. Also,
based on the detection of the vehicle position detecting device,
the elevation of the own vehicle position is determined. Therefore,
a sensor, which directly detects the elevation of the own vehicle
position or the external atmospheric pressure, is unnecessary.
Therefore, the structure can be simplified.
[0046] Note that, as a modification of the second embodiment, the
pressure differential between the interior and the external of the
casing 15 may alternatively serve as a drive force to inflate and
deform the bag member 31 without use of the heat generating element
32. When the inflation deformation of the bag member 31 by the
drive force of the pressure differential reliably seals the
breathing hole 22, the vehicle position detecting device and the
heating device are not required. This simplifies the structure of
the hard disk drive of the modification of the second embodiment of
the present invention.
Third Embodiment
[0047] FIG. 6 shows the third embodiment of the present invention.
Note that, in the third embodiment, the present invention is also
applied to a hard disk drive, which is assembled in a car
navigation system, and which stores geographic data. The structure
of a sealing device for sealing (blocking up) the breathing hole 22
in the third embodiment is different from that in the first
embodiment. Thus, similar components similar to those in the first
embodiment are indicated by the same numerals. New illustration and
detailed description of the similar components are omitted so that
only different points are described below.
[0048] In the third embodiment of the present invention shown in
FIGS. 6A, 6B, a cover member 33 serving as the sealing device,
which seals the breathing hole 22 in accordance with the external
atmospheric pressure, is provided inside the breathing hole 22 in
the casing 15 (e.g., provided to the inner face of top cover 15b).
The cover member 33 is made of a sheet metal. The cover member 33
is slidably displaceably provided along the inner face of the top
cover 15b in a right and left direction in FIG. 6 between an open
position and a sealing position. The open position is a position,
which opens the breathing hole 22 as shown in FIG. 6A. The sealing
position is a position for sealing the under surface side of the
breathing hole 22 as shown in FIG. 6B.
[0049] Also, an actuating device 34 for slidably displacing the
cover member 33 between the open position and the sealing position
is provided as shown in FIGS. 6A, 6B. The actuating device 34
includes, for example, a solenoid or a piezoelectric element. In
the normal state, the cover member 33 is located at the open
position. When the navigation control circuit 2 detects that the
elevation (altitude) of the own vehicle position is equal to or
more than the threshold value (e.g., 3,000 m) based on the signal
from the GPS receiver 3 and the like, the navigation control
circuit 2 outputs to the hard disk drive 12 a displacement command
signal for displacing the cover member 33 toward the sealing
position. When the elevation of the own vehicle position becomes
less than the threshold value afterwards, the navigation control
circuit 2 is adapted to output a return command signal for
returning the cover member 33. The controller in the hard disk
drive 12 is adapted to control the actuating device 34 based on
these received displacement command signal and return command
signal.
[0050] The cover member 33 is in the open position as shown in FIG.
6A in a normal state to open the breathing hole 22. Typically, the
normal state is a state, where the elevation of the own vehicle
position has not reached the threshold value (e.g., the external
atmospheric pressure is about 1 atm). In contrast, the cover member
33 is adapted to be displaced to the sealing position to seal the
breathing hole 22 as shown in FIG. 6B when the elevation of the own
vehicle position becomes equal to or more than the threshold value
(e.g., 3,000 m). Note that the cover member 33 is returned to the
open position when the elevation of the own vehicle decreases.
Also, note that at this time, a threshold value for a case, where
the cover member 33 is displaced to the sealing position, may be
different from a threshold value for a case, where the cover member
33 is returned to the open position such that a control with
hysteresis is performed.
[0051] In the third embodiment, the cover member 33, which serves
as the sealing device, and the actuating device 34, which drives
the cover member 33, are provided. As a result, similar to the
first and second embodiments, when used in a high elevation area,
the appropriate clearance between the face of the hard disk 16 and
the magnetic head 18 can be ensured. Therefore, while limiting
damage of the hard disk 16, the access to the hard disk 16 can be
enabled. The breathing hole 22 is surely opened or sealed,
furthermore. Also, the structure for this purpose (reliable opening
and sealing of the breathing hole 22) can be comparatively
simplified.
[0052] Note that, in each of the above embodiments, the present
invention is applied to the hard disk drive, which is assembled in
the car navigation system 1 (vehicle navigation system). However,
the present invention may be applied to an apparatus, which is
assembled in a car audio system to store music data. The position
for providing the breathing hole 22 of the casing 15 may be changed
in various manners. In addition, the above described threshold
values (the altitude of 3,000 m, the atmospheric pressure of 0.7
atm) for sealing the breathing hole are only one example.
[0053] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader terms is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *