Hard disk drive for vehicle

BRIEF DESCRIPTION OF DRAWINGS

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:

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;

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;

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;

FIG. 3 is a perspective view showing a filter member of a rear of the top cover;

FIG. 4 is a block diagram schematically illustrating an electric structure of a car navigation system;

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;

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;

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

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

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.

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.

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.

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.

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

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.

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.

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.

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).

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.

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).

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

Hard disk drive for vehicle

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CPC

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Description

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Priority Claims (1)