PATENT DOCUMENT

Publication Number: US-7307228-B2
Application Number: US-89085604-A
Country: US
Kind Code: B2

Title: Method and apparatus for detecting free fall

Abstract:
A data processing system including a data storage device having data stored on a data storage medium. Within said data processing system, a system electronics is operatively coupled to a sensor and to said data storage device. When the sensor senses a change in gravitational or inertial acceleration of said data processing system, it alerts system electronics to temporarily park a read/write head in a safe position.

Claims:
1. A portable electronic device, comprising:
 a data storage device having data stored on a data storage medium; and 
 an acceleration detector coupled to the data storage device to detect a change in an acceleration of the portable electronic device and to configure the data storage device from a first operating state into a second operating state in response to the detection, wherein the acceleration detector includes a flexible non-electrically conductive support material,
 an electrically conductive casing coupled to the flexible non-electrically conductive support material, and 
 a beam having a first end and a second end supported by the flexible non-electrically conductive support material. 
 
 
     
     
       2. The portable electronic device of  claim 1 , wherein the portable electronic device is a digital camera. 
     
     
       3. The portable electronic device of  claim 1 , wherein the portable electronic device is a musical playback device. 
     
     
       4. The portable electronic device of  claim 1 , wherein the portable electronic device is a portable computer system. 
     
     
       5. The portable electronic device of  claim 1 , further comprising system electronics coupled to the data storage device and the acceleration detector, wherein in response to the detection, the system electronics execute a predetermined process, which in part transforms the data storage device from the first operating state into the second operating state. 
     
     
       6. The portable electronic device of  claim 5 , wherein the predetermined process, when executed, transforms the data storage device from the first operating state into the second operating state. 
     
     
       7. The portable electronic device of  claim 1 , wherein during the second operating state, data stored in the data storage device is inaccessible. 
     
     
       8. The portable electronic device of  claim 1 , wherein the beam is rigid or flexible. 
     
     
       9. The portable electronic device of  claim 8 , wherein the second end of the beam contacts the casing when the acceleration detector is at rest. 
     
     
       10. The portable electronic device of  claim 8 , wherein the second end of the beam does not contact the casing during free fall. 
     
     
       11. The portable electronic device of  claim 8 , wherein the acceleration detector further comprises a mass attached to the second end of the beam. 
     
     
       12. The portable electronic device of  claim 11 , wherein the mass contacts the casing when the acceleration detector is at rest. 
     
     
       13. The portable electronic device of  claim 12 , wherein the mass, the casing, and the beam are each electrically conductive. 
     
     
       14. The portable electronic device of  claim 11 , wherein the mass does not contact the casing when the acceleration detector is at rest. 
     
     
       15. The portable electronic device of  claim 8 , further comprising means to couple the acceleration detector to a substrate. 
     
     
       16. The portable electronic device of  claim 15 , wherein the means is one of at least one lead or one conductive pin. 
     
     
       17. The portable electronic device of  claim 1 , wherein the casing is closed at both ends and filled with an inert gas or non-electrically conductive liquid. 
     
     
       18. A method performed by a portable electronic device, the method comprising:
 detecting a change in an acceleration of the portable electronic device using an acceleration detector disposed within the portable electronic device; and 
 executing a predetermined process in response to the detection, wherein the acceleration detector includes
 a flexible non-electrically conductive support material, 
 an electrically conductive casing coupled to the flexible non-electrically conductive support material, and 
 a beam having a first end and a second end supported by the flexible non-electrically conductive support material. 
 
 
     
     
       19. The method of  claim 18 , further comprising transforming a data storage device of the portable electronic device from a first operating state into a second operating state in response to the detection. 
     
     
       20. The method of  claim 18 , wherein the portable electronic device is a digital camera. 
     
     
       21. The method of  claim 18 , wherein the portable electronic device is a musical playback device. 
     
     
       22. The method of  claim 18 , wherein the portable electronic device is a portable computer system. 
     
     
       23. The method of  claim 18 , wherein the beam is rigid or flexible. 
     
     
       24. The method of  claim 23 , wherein the second end of the beam contacts the casing when the acceleration detector is at rest. 
     
     
       25. The method of  claim 23 , wherein the second end of the beam does not contact the casing during free fall. 
     
     
       26. The method of  claim 23 , wherein the acceleration detector further comprises a mass attached to the second end of the beam. 
     
     
       27. The method of  claim 26 , wherein the mass contacts the casing when the acceleration detector is at rest. 
     
     
       28. The method of  claim 27 , wherein the mass, the casing, and the beam are each electrically conductive. 
     
     
       29. The method of  claim 26 , wherein the mass does not contact the casing when the acceleration detector is at rest. 
     
     
       30. The method of  claim 23 , further comprising means to couple the acceleration detector to a substrate. 
     
     
       31. The method of  claim 30 , wherein the means is one of at least one lead or one conductive pin. 
     
     
       32. The method of  claim 18 , wherein the casing is closed at both ends and filled with an inert gas or non-electrically conductive liquid. 
     
     
       33. A data processing system, comprising:
 a data storage device having data stored on a data storage medium; and 
 an acceleration detector coupled to the data storage device to detect a change in an acceleration of the portable electronic device and to configure the data storage device from a first operating state into a second operating state in response to the detection, wherein the acceleration detector includes a flexible non-electrically conductive support material,
 an electrically conductive casing coupled to the flexible non-electrically conductive support material, and 
 a beam having a first end and a second end supported by the flexible non-electrically conductive support material.

Description:
This application is a continuation application of U.S. patent application Ser. No. 10/348,465, filed on Jan. 21, 2003, now U.S. Pat. No. 6,768,006, which is a divisional application of U.S. patent application Ser. No. 09/678,541, filed on Oct. 2, 2000, now issued as U.S. Pat. No. 6,520,013. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to data storage devices, such as hard disc drive assemblies and data processing systems, generally. In particular, the invention relates to data storage devices that are subject to free fall or other changes in acceleration, for example, storage devices used in portable computers, cameras, onboard vehicular computers, and similar electronic devices. ‘Free fall’ produces a change in the force, i.e. acceleration, of gravity as perceived in the frame of reference in which the data storage device is at rest. 
     BACKGROUND 
     Portable electronics devices such as digital and film cameras, notebook computers, and onboard vehicular computers containing data storage devices such as hard disk drives are often dropped, bumped, or bounced. When an object is dropped or falls back to earth after a bounce, the object experiences free fall, a period of minimal or zero gravitational force. ‘Free fall’ produces a change in the force, i.e. acceleration, of gravity as perceived in the frame of reference in which the data storage device is at rest. On earth, free fall usually immediately precedes an impact with a surface that may damage operating or unparked data storage devices, their spinning disks, actuators, and read/write heads. A parked data storage device is one in which the actuator has temporarily moved the head away from the spinning disk, and the actuator and head are safely locked in a fixed position in preparation for transportation or an anticipated impact. Because a data storage device can be safely prepared for an impact in a time shorter than the time it takes the data storage device to complete its fall, the present invention has great utility in preventing or mitigating the damage formerly experienced by data storage devices that were dropped down stairs, dropped onto concrete, asphalt or other hard surfaces, or that were bounced into the air from vehicles contacting speed bumps, waves, or turbulent air pockets at high speeds and slammed back down again. 
     In simplest form, a data storage device, such as a disc drive, consists of a spinning disk and an actuator movably positioned near the surface of the disk. The surface of the disk typically contains multiple annular tracks or grooves in which data is stored and manipulated and from which data is retrieved by a read/write head (e.g. a magnetic or an optical head) positioned on the actuator. 
     It is important that the data storage head be kept as free from vibrations and/or sudden acceleration or deceleration as possible because the head reads data from and writes data to the multiple annular tracks on the spinning disk. Sudden acceleration or deceleration or excessive vibration of the disk drive can cause the head to skip tracks, to encode information incorrectly on the wrong track or tracks, to erase data previously encoded on the disk, or to dent the disk surface. Several types of sensors have been developed to mitigate or to prevent excessive vibration from harming recorded data, but no sensors measuring changes in the force, i.e. acceleration, of gravity in the frame of the data storage device, existed prior to conception and development of this invention. 
     One type of vibration detection and protection system found in the field of data storage devices is known as the off track signal or OTS. Generated by an electrical component of a data processing system, such as a magnetic hard disk, or CD, or DVD drive, the OTS is derived from the signals generated by the magnetic hard disk or CD head as it follows data tracks on the disk. The amplitude of the OTS is designed to vary in direct proportion to the amount of vibration experienced by the data processing system. Thus, the more vibration experienced by the data processing system, the more the amplitude of the OTS increases. The system electronics of the data storage device monitors the amplitude of the OTS and temporarily disables the ability of the head to write and/or read information to or from the data storage device whenever the OTS amplitude matches or exceeds a predetermined amplitude. 
     Although the OTS system protects data stored on the data storage device from being erased or overwritten by the head, it does not prevent damage resulting from the head popping up and down onto the spinning disk when the data storage device is dropped and impacts a surface. For example, if the head slams downward onto a spinning data medium device, such as a CD or DVD or magnetic hard disk, data may be irretrievably lost, the head may be severely damaged, and the CD, DVD, or magnetic hard disk may be irreparably dented. 
     A second kind of sensor is found in the unrelated automobile field. Sensors in this field are used to deploy various safety devices, such as airbags, whenever an accident occurs. Such sensors passively wait for an impact to occur and then rapidly deploy safety devices before a human&#39;s body impacts hard, bone-crushing surfaces within the automobile&#39;s interior cabin such as dashboards, windshields, and steering wheels. They cannot predict the possibility of an imminent impact, nor can they detect the absence of a gravitational field as some embodiments of the present invention can. Moreover, sensors found in the automobile field have not been used to protect data in data processing systems such as hard disk drives. 
     A third type of vibration countermeasure found in the field of consumer portable electronic devices is specifically designed to combat the “skips” commonly associated with audio playback of CD-ROMS and DVD&#39;s. “Skips” are miniature, but discernable, periods of silence in music or other audio broadcast material that occur whenever a musical playback device is jostled, vibrated, or dropped. This countermeasure is typically called a “buffering system.” In simplest form, a buffering system incorporated within a musical playback device reads audio data from the spinning disk during playback of the disk at a rate slightly faster than the rate at which the audio data is broadcast. By reading “ahead” of the broadcast, a portion of the audio data is continually saved up and stored in the buffer. Whenever a “skip” occurs, the buffering system ensures a smooth, unbroken audio playback by filling the “skip” with audio data from the buffer. Unlike, the present invention, however, the buffering system does not protect the data storage device or its data actuating head from damage caused by dropping or vibrating the device. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment of the present invention, as illustratively described herein, a data processing system is provided. Within the data processing system, system electronics is operatively coupled to a hard disk drive assembly and to an acceleration sensor, which can sense gravitational acceleration. The system electronics monitors the acceleration sensor to determine whether the sensor&#39;s switch is open or closed. If an open switch indicating a free fall is detected, the system electronics protects the data read/write head and data storage medium by temporarily parking the head in a safe position where it cannot impact the data storage medium surface. A safe position can include a parked position off to one side of a data storage medium or a secured operating position that prevents vibration from damaging the read/write head or the data storage medium. According to one aspect of the present invention, the term secured includes fixed, semi-fixed, and movable operating positions. 
     According to an alternate aspect of the present invention, a sensor is provided that can detect changes in gravitational and/or inertial acceleration. In an exemplary embodiment, the sensor includes an electrically conductive tube having two ends. A supporting material may close one end of the tube. The other end may be open or closed. Within the interior of the tube, one end of a flexible beam or wire is inserted into the supporting material. Gravity flexes the opposite end of the beam or wire into contact with the tubular case, creating a closed electrical circuit. Whenever the force of gravity lessens, the second end of the beam or wire breaks contact with the tube, creating an open switch. 
     According to another aspect of the present invention, a sensor is provided that can detect changes in gravitational and/or inertial acceleration. Illustratively, this sensor includes a closed cylinder. Within the interior of the cylinder, a centrally positioned, electrically conductive beam juts upward from the cylinder&#39;s base. A circle of insulating material surrounds the base of the beam and creates a gap between the beam and the cylinder&#39;s oblique, conical interior walls. The beam and cylinder walls are electrically conductive. Gravity holds an electrically conductive sphere in contact with both the beam and a oblique surface, creating a closed circuit. Any lessening of the gravitational force causes the sphere to break contact with either or both of the beam and interior walls, creating an open circuit. 
     Various examples for practicing the invention, other advantages, and novel features thereof will be apparent from the following detailed description of various illustrative preferred embodiments of the invention, reference being made to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements. 
         FIG. 1  is an exemplary view of a data processing system in free fall. As shown, the data processing system contains a hard disc operatively coupled to a read/write head. An embodiment of the present invention has sensed free fall and safely parked the actuator and magnetic head prior to impact. 
         FIG. 2  is a schematic illustrating how system electronics within a data processing system can monitor an embodiment of the present invention and command a data storage device, such as a hard disc drive, to park an actuator and magnetic head when a state of free fall is detected. 
         FIG. 3  illustrates an exemplary embodiment of the present invention in the at rest state according to one aspect of the present invention. 
         FIG. 4  illustrates an exemplary embodiment of the present invention in a state of free fall according to an aspect of the present invention. 
         FIG. 5  illustrates a data storage device; such as a hard disc drive, and its associated actuator and magnetic head in operation. Dotted lines indicate the parked position of the actuator and head. 
         FIG. 6  illustrates an exemplary embodiment of the present invention in the at rest state according to another aspect of the invention 
         FIG. 7  illustrates an exemplary embodiment of the present invention in a state of free fall according to another aspect of the invention. 
         FIG. 8A  is a side view illustrating an exemplary embodiment of the present invention in the at rest state according to another aspect of the present invention. 
         FIG. 8B  is a side view illustrating an exemplary embodiment of the present invention in a state of free fall according to another aspect of the present invention. 
         FIG. 8C  is an overhead view illustrating an exemplary embodiment of the present invention in the at rest state according to another aspect of the present invention. 
         FIG. 8D  is an bottom view illustrating an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The acceleration sensor shown illustratively in the accompanying drawings is particularly suited to be of relatively small size for use in data processing systems used in notebook computer systems, digital cameras, music recording and playback devices, automobiles, marine vessels, aircraft, spacecraft, and similar equipment. Additionally, the embodiments of the present invention may be especially suited for use in a variety of additional applications not having data storage devices coupled to actuators and heads where it is desired to sense acceleration or detect a state of free fall. For example, this invention could be used to trigger inflation of a cushion to soften the impact for a dropped camera. 
       FIG. 1  shows a perspective view of a hard drive system. Typically, a data storage device  103 , such as a hard disc drive system, is installed within a main housing of a computer  100 , such as the notebook computer illustratively shown. However, it is understood that the invention is not limited to computers such as the one illustratively shown in  FIG. 1 . Rather, the invention applies to and may complement any data storage device  103  wherever such device is located. For example, and for purposes of illustration only and not limitation, a data storage device  103 , such as a hard disc drive, may be located within a camera or other portable consumer electronic device, within an onboard vehicular computer, an elevator, an amusement park ride, etc. Moreover, in other embodiments, the data storage device may store analog data instead of digital data and the data storage device may use optical mechanisms to read and/or write the data. 
     A data storage device  103 , such as a hard disc drive, contains a data storage medium  102  such as a hard disc and an actuator  104  having a magnetic read/write head  106 . Read/write head  106  reads and writes data to tracks  108  on spinning data storage medium  102 , such as a hard disc. Acceleration sensor  110  and system electronics  112  are electrically coupled to the hard disc drive  103  such that when acceleration sensor  110  detects a state of free fall in which there is substantially zero perceived gravitational acceleration, system electronics  112  commands the disc drive  103  to put the actuator  104  and magnetic (or optical) head  106  in a parked position before the fall is completed. Alternatively, sensor  110  can be used to detect changes in non-gravitational (inertial) acceleration, an acceleration or de-acceleration of the sensor&#39;s reference frame caused objects such as automobile or aircraft engines or vehicular brakes. 
     Preferably, acceleration sensor  110  is located near or at the center of mass of the object prone to free fall so that sensing of the free fall state will be independent of any rotation and centrifugal forces present during the fall. However, the invention includes all positions of acceleration sensor  110  and all locations for system electronics  112  that perform the monitoring and command functions described above. Illustratively, acceleration sensor  110  may be positioned as an integral component of data storage device  103  itself, or may be positioned as a non-integral component of data storage device  103  elsewhere within a data processing system. 
     In a preferred embodiment, acceleration sensor  110  is integrated with a data processing system containing a hard drive disk assembly  103 . In a preferred embodiment, sensor  110  is incorporated within system by soldering leads  120  and  122  to pads on a substrate  124 , for example, a printed circuit board. 
       FIG. 2  shows a schematic representation illustrating how system electronics  112  monitors acceleration sensor  110  and commands data storage device  103 , such as a hard disc drive to park actuator  104  and magnetic head  106  in a safe position when a free fall is indicated or the gravitational force otherwise approaches zero. 
     Acceleration sensor  110  is a simple electronic switch that remains closed when system  100  is at rest, and opens when system  100  begins to free fall. System electronics  112  continuously or periodically monitors acceleration sensor  110  to detect whether the switch is closed or open. Immediately upon detecting an open switch, system electronics  112  transmits a command to data storage device  103 . Upon receiving this command, data storage device  103  immediately parks actuator  104  and magnetic head  106  in a safe position  126 , as shown in  FIG. 5 . Safe position can be either a location to the side of data storage medium  102 , as illustrated in  FIG. 5 , or a locked operating position that prevents head  106  from writing to the wrong track  108  and that prevents head  106  from vibrating against data storage medium  102 . For example, in an optical drive, a safe position  126  could be a location where the objective lens is pinned against its upper stop. 
       FIG. 3  shows a cross-sectional side view of a preferred embodiment of acceleration sensor  110 . Sensor  110  includes a casing connection  116  and a beam connection  118 . Casing connection  116  is connected to a first lead  120 , and beam connection  118  is connected to a second lead  122 .  FIG. 3  shows sensor  110  in an at rest position. In this position, gravity pulls electrically conductive mass  128 , attached to one end of electrically conductive beam  130 , into contact with electrically conductive casing  132 . Preferably, one end of beam  130  is supported by insulating support material  138 , which may be flexible or rigid. In the illustrated embodiment, insulating support material  138  is rigid. 
     Beam  130  may have any aspect ratio, meaning that beam  130  can have any cross-sectional shape. As exemplified in  FIG. 3 , beam  130  is flexible and electrically conductive. Preferably, the flexural constant of beam  130  is such that mass  128  contacts casing  132  when acted on by a gravitational force. Specifically, the flexural characteristics of the beam should be chosen so that two conditions are met:
         1. The at rest gravitational force bends the beam, or beam/flexible mount combination, so that the beam or beam/mass makes electrical contact with the casing.   2. The lack of gravitational force during free fall allows the beam or flexible mount to straighten and break the electrical contact between the beam or beam/mass and the casing.       

     In a preferred embodiment, insulating support material  138  is a rigid material such as glass, but other insulating materials such as plastic, epoxy, ceramic, etc. may also be used. 
     In an exemplary embodiment, free end of the beam  130  may be weighted with a mass  128  to increase gravitational deflection and flex beam  130  such that the mass  128  contacts the electrically conductive casing  132 . However, the invention can operate without mass  128 . For example, in an illustrative embodiment, the shape of the beam  130 , its dimensions, and the material comprising the beam  130  can be chosen such that the weight of the cantilevered portion of beam  130  itself flexes the free end of beam  130  into contact with a electrically conductive casing  132 . 
     If a mass is attached to the free end of beam  130 , the mass  128  may take almost any size and shape since the size and shape of the mass  128  are not essential to the operation of the invention. It makes no difference whether the shape of the mass  128  is circular, squarish, polygonal, or triangular, as long as the mass is made of or carries an electrically conductive material and contacts electrically conductive casing  132  when the data storage device  103  is at rest. The preferable shape of the mass  128 , as illustratively shown in the Figures is spherical. 
     According to one aspect of the present invention, the beam  130  and mass  128  are made of conductive materials or carry conductive means. Thus, electrical contact is made whenever either the free end of beam  130  or mass  128  touches casing  132 . In this manner, the invention acts as an electrical switch, closed when at rest and open when in free fall. Beam  130  and mass  128  may be formed as one piece of electrically conductive material, or from separate pieces joined together by any suitable method, including, but not limited to, screwing, gluing, soldering, etc. 
     It should be noted that the dimensions of the components of acceleration sensor  110  are scalable, meaning of course, that one skilled in the art can determine the mechanical coefficients of non-electrically conductive insulating material  138  and beam  130  easily and without undue experimentation. Accordingly, one skilled in the art could readily manufacture acceleration sensor  110  illustrated in  FIGS. 1-3  in any one of a number of possible sizes. In a preferred embodiment, however, acceleration sensor  110  is approximately 4-6 mm long, 2-3 mm wide and 2-3 mm high. These preferred dimensions, however, are given only for purposes of illustration, and are not meant to limit the size of acceleration sensor  110  in any fashion. Rather the invention includes all sizes of acceleration sensor  110 . 
     Preferably, as illustratively shown in  FIG. 3 , the sensor  110  described above is enclosed by a tubular casing  132  formed of an electrically conductive material. In an exemplary embodiment, insulating support material  138  completely fills one end of the tubular casing, while the second end is also closed. The interior of casing  132  may be filled with a gas of the type well known in the art for sealing the interiors of electronic components to prevent corrosion of electrical contacts. However, it is not necessary to close the second end of the casing, nor is it necessary that the casing be tubular. Rather, the second end of the casing may be left open, and the casing may take almost any structural form, including, but not limited to tubes, circles, squares, triangles, polygons, etc. In a preferred embodiment, one end of casing  132  is connected to the first electrically conductive lead  122 , while the beam connection  118  is connected to a second electrically conductive lead  120 . 
     In an alternative embodiment, the present invention may be made and operated without a tubular casing  132 . For example, fixed end of beam  130  could be supported by insulating support member  138  and operatively connected via beam connection  118  to electrically conductive lead  120 , such that the free end of beam  130  or mass  128  was positioned to make physical contact with an electrically conductive pad when the data storage device  103  is at rest. 
       FIG. 4  shows acceleration sensor  110  in a free fall position. In the absence of a gravitational force (e.g. during free fall), physical contact with the casing  132  is broken as the beam  130  straightens to an approximately horizontal position shown in  FIG. 4 . Thus, sensor  110  functions as a switch, closed when at rest, open when in free fall. Breaking physical contact with casing  132  immediately alerts system electronics  112  (shown in  FIG. 1 ) to command data storage device  103 , such as a hard disc drive ( FIG. 1 ) to park actuator  104  ( FIG. 1 ) containing magnetic read/write head  106  ( FIG. 1 ) in a safe position  126  (shown in  FIG. 5 ). Alternatively, the same method may be used with another embodiment of the present invention in which mass  128  makes electrical contact with casing  132 . In such an embodiment, the switch would be open in the at rest position and closed during free fall. From rest, an object within the Earth&#39;s gravitational field free falls 0.5 meters in 0.32 seconds. The time required to process a command and park the head in a disc drive is typically less than 0.04 seconds. Thus, the head can be parked in a safe position well before the fall is completed. 
       FIG. 5  is a top-down view of hard disk drive showing actuator  104  and magnetic read/write head  106  in an operating position. A safe parked position  126  is indicated by broken lines. Data storage device  103 , such as a hard disc drive is operatively coupled to system electronics  112  (not shown). In response to commands from system electronics  112 , data storage device  103  moves actuator  104  and magnetic read/write head  106  rapidly sideways in a plane approximately parallel to the disk  102  between its operating position and a parked position, which is illustratively depicted as safe position  126  in  FIG. 5 . 
       FIG. 6  is a side view of sensor  110  according to a preferred embodiment of the present invention. In this Figure, sensor  110  is shown at rest in a gravitational field. In this embodiment, beam  230  is rigid. One end of beam  230  is inserted into insulating support material  238 , while the other end is attached to mass  228 . Mass  228  may be of any shape, but preferably is spherical. According to one aspect of the present invention, insulating support material  238  is flexible and adheres to electrically conductive beam connection  218 , which is also flexible. Illustratively, insulating non-electrically conductive support material  238  is a semi-rigid or flexible material such as rubber. 
     When at acceleration sensor  110  is at rest, gravitational force pulls free end, including mass  228 , of rigid electrically conductive beam  230  into contact with electrically conductive casing  232 . When tilted by a gravitational force, rigid beam  230  deforms insulating support material  238  as shown. In an exemplary embodiment according to one aspect of the invention, beam  230  and support material  238  may both be flexible. 
       FIG. 7  illustratively shows sensor  210  during free fall, a period of minimal gravitational acceleration. During free fall, minimal gravitational acceleration and the restoring forces in deformed insulating support material  238  cause mass  228  to break contact with casing  232  and to return approximately to a position delineated by horizontal axis  227 . 
       FIG. 7  shows an illustrative embodiment of the present invention in which beam  230  is formed of a rigid, electrically conductive material. In this embodiment, rigid beam  230  is capable of moving between an at-rest position and a free-fall position. Preferably, rigid beam  230  is supported at one end by a semi-rigid or flexible, non-electrically conductive insulating support material  238 . 
       FIGS. 8A-8D  show various views of an acceleration sensor according to particular exemplary embodiments of the present invention.  FIG. 8A  is a cross-sectional side view of a gravitational acceleration sensor  110 . In this illustrative embodiment, acceleration sensor  110  includes a casing  332 , which rests on non-conducting insulating base  338 , an electrode  330 , and a spherical mass  328 . This embodiment, like others previously described, acts as an electrical switch, closed when the sensor is at rest and open during free fall. In the at rest position, mass  328  contacts both beam  330  and casing  332 . During free fall, mass  328  does not contact beam  330  and case  332 . The phrase “does not contact beam  330  and case  332 ” further includes situations where: mass  328  contacts casing  332  only; mass  328  contacts beam  330  only; or mass  328  does not contact beam  330  or casing  332 . 
     Non-conducting insulating base  338  may be formed of any suitable insulating material known in the art. The insulating material may be either fixed or semi-rigid. In a preferred embodiment, insulating base  338  may be made as thick or as thin as practicable. Conducting inner electrode  330  (hereinafter beam  330 ) is vertically positioned in insulating base  338 . According to an aspect of the present invention, a top portion of beam  330  juts out into internal cavity  312  of casing  332 , while a middle portion passes through insulating base  338 . A bottom portion of beam  330 , (hereinafter first conducting pin  320 ) extends past the exterior of insulating base  338  and removably inserts into a substrate such as a printed circuit board  324 . Similarly, a second conducting pin  322 , vertically positioned substantially parallel to beam  330 , also extends past the exterior of insulating base  338  and removably inserts or connects into a substrate such as a printed circuit board  324 . Electrically conductive traces  333  and  334  connect sensor  310  to system electronics  112  (not shown), which monitor sensor  310  and command data storage device  103  (not shown) to park the magnetic or optical head whenever conducting ball  328  (hereinafter mass  328 ) breaks electrical contact between beam  330  and casing  332 . 
     According to an aspect of the present invention, beam  330 , conducting pins  320  and  322 , mass  328 , and casing  332  are each made of or carry electrically conductive materials. Examples of such electrically conductive materials include, but are not limited to: copper, brass, silver, gold, steel, and similar materials. 
     According to another aspect of the present invention, a bottom portion of the interior of casing  332  is angled to form an oblique surface  314 , which extends from a point approximately located at horizontal axis  307  down to insulating base  338  such that a ringed gap  340  encircles beam  330 . In a preferred embodiment, mass  328  is a sphere and gap  340  is not greater than the diameter of mass  328 . Gap  340  has a width sufficient that mass  328  contacts both casing  332  and beam  330  simultaneously when sensor  110  is at rest, and a width sufficient that insulating base  338  insulates beam  330  from casing  332 . Illustratively, oblique surface  314  angles downwards at approximately a 45 degree angle to channel mass  328  into electrical contact with beam  330  when mass  328  is acted upon by a gravitational force. However, oblique surface  314  may be sloped at almost any angle less than 90 degrees so long as it channels mass  328  into electrical contact with beam  330 . According to another aspect of the invention, the interior and exterior surfaces of casing  332  are cylindrical, while the exterior of casing  332  may be of any shape. Internal cavity  312  may be filled with an inert gas or non-conducting liquid to prevent corrosion of beam  330 , casing  332 , and mass  328 . As used herein “mass  328 ” means contactor. 
       FIG. 8B  illustrates how sensor  310  operates in the absence of a gravitational force. The unique oblique interior walls  314  permit the mass  328  to break away from the beam  330  and/or casing  332  when the force of gravity is reduced to zero by free fall of the device. An open circuit between the beam  330  and casing  332 , implying the absence of a gravitational force, signals system electronics  112  ( FIG. 1 ) to command hard disk drive  103  ( FIG. 1 ) to park magnetic data actuating head  106  ( FIG. 1 ) in a safe position  126  ( FIG. 5 ). 
       FIG. 8C  is a top-down view of gravitational sensor  310  illustratively showing how oblique surface  314  holds mass  328  in contact with beam  330  when sensor  310  is acted upon by a gravitational force. In this view, the top cover of sensor  310  has been removed. 
     The illustrative dimensions of sensor  310  and its components are now described. According to an aspect of the present invention, the diameter of casing  332  is approximately 10 mm, the depth, approximately 5 mm. The diameter of mass  328  measures approximately 2 mm, while the diameter of beam  330  measures approximately 2 mm. The diameter of the ringed gap  340  of insulating material  338  surrounding beam  330  measures approximately 3 mm. It will be understood that these ranges are provided only for purposes of illustration. The diameter of the sensor  310  and the diameters of its components are free design parameters. The values shown or described are informative and exemplary only and should not be construed as limiting the invention in any way. 
       FIG. 8D  shows a bottom view a gravitational sensor according to an aspect of the present invention. In this exemplary embodiment, first conductive pin  320  is centrally mounted within insulating base  338 . Illustratively, second conductive pin  322  may be positioned anywhere within or without the circumference of insulating base  338  provided second conductive pin  322  does not electrically contact first conductive pin  320 . 
     The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The description was selected to best explain the principles of the invention and practical application of these principles to enable others skilled in the art to best utilize the invention in various embodiments and in various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention not be limited by the specification, but be defined by the claims set forth below.

Metadata:
Filing Date: 20040713
Publication Date: 20071211
Grant Date: 20071211
Priority Date: 20001002
Inventors: WEHRENBERG PAUL JAMES
Assignee: APPLE INC
CPC Classifications: [{"code": "G11B19/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "G11B21/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G11B19/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G11B21/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G11B19/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G11B19/04", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 24723227