PATENT DOCUMENT

Publication Number: US-8132197-B2
Application Number: US-84191010-A
Country: US
Kind Code: B2

Title: Mounting objects on a turntable

Abstract:
The embodiments herein describe an apparatus and method for a reduced Z stack slot loading optical disc drive (ODD). In one embodiment, an optical disc mounting assembly can be used to chuck an optical disc to a turntable. The optical disc mounting assembly can include a hub spring for spring loading a hub and a clamping mechanism pivotally connected to the hub. In the described embodiment, in an extended position, the clamp is used to secure the optical disc to the turntable. The clamping mechanism can include a clamp pivotally attached to the hub at a pivot point. In the absence of the optical disc, the clamp is retracted and secured within a recess in the optical disc mounting assembly. In the presence of the optical disc, the mounting assembly chucks the optical disc to the turntable using the clamp and hub.

Claims:
What is claimed is: 
     
       1. A reduced Z stack height slot loading optical disc drive (ODD), comprising:
 a slot arranged to receive an optical disc; 
 a turntable having a central opening and a platen arranged to provide a surface upon which the optical disc is secured; and 
 a reduced Z drive mounting assembly used for chucking an optical disc to the turntable, the reduced Z drive mounting assembly comprising: 
 a hub assembly, the hub assembly comprising:
 a ferritic hub aligned with the turntable central opening and shaped to accommodate an optical disc central hole, 
 an interior surface shaped to act as a cam, 
 a hub spring arranged to generate a spring force used to extend the hub into the turntable central opening in the presence of the optical disc, 
 
 at least one ferritic securing clamp pivotally attached to the mounting assembly at a pivot point, and 
 an electromagnet arranged to create an induced magnetic field that attracts the ferritic hub and clamp, wherein the magnetic attraction overcomes the spring force and causes the hub and the at least one clamp to retract into the mounting assembly. 
 
     
     
       2. The optical disc drive as recited in  claim 1 , wherein when the electromagnet is de-energized, the force generated by the hub spring causes a portion of the ferritic hub and at least one ferritic securing clamp to extend out of the mounting assembly. 
     
     
       3. The optical disc drive as recited in  claim 1 , wherein the electromagnet is positioned at the base of the mounting assembly substantially underneath the ferritic hub and at least one ferritic securing clamp. 
     
     
       4. The optical disc drive as recited in  claim 1 , wherein the ferritic securing clamp contacts the interior surface of the ferritic hub, creating a cam movement action that causes the clamp to pivot in response to displacement of the hub. 
     
     
       5. The optical disc drive as recited in  claim 1 , further comprising a disc input sensor that sends an on signal to the electromagnet causing the electromagnet to energize and create an induced magnetic field. 
     
     
       6. The optical disc drive as recited in  claim 1 , further comprising a turntable center sensor that sends an off signal to the electromagnet causing the electromagnet to de-energize and collapse the induced magnetic field when an optical disc is substantially centered over the turntable center opening. 
     
     
       7. The optical disc drive as recited in  claim 1 , further comprising rotation motor elements to drive the turntable to rotate about an axis of rotation during device operation. 
     
     
       8. The optical disc drive as recited in  claim 7 , wherein the rotation motor elements are positioned within the turntable. 
     
     
       9. The optical disc drive as recited in  claim 7 , wherein the rotation motor elements are positioned outside of the turntable. 
     
     
       10. The optical disc drive as recited in  claim 9 , wherein the rotation motor elements are coupled to the outer surface of the turntable to drive the rotation of the turntable. 
     
     
       11. A method of securing an optical disc to the turntable of an optical disc drives comprising the steps of:
 retracting a ferritic hub and at least one ferritic clamp into the mounting assembly using magnetic attractive forces generated by an induced magnetic field; 
 centering an optical disc substantially over the turntable central opening; 
 collapsing the induced magnetic field within the mounting assembly; and, 
 extending the ferritic hub and at least one ferritic clamp out of the mounting assembly through the turntable central opening such that at least one ferritic clamp makes contact with the optical disc and secures the optical disc to the turntable. 
 
     
     
       12. The method as recited in  claim 11 , wherein the ferritic hub and at least one ferritic clamp are extended out of the mounting assembly using a force provided by a hub spring. 
     
     
       13. The method as recited in  claim 11 , wherein the ferritic hub and at least one ferritic clamp are extended out of the mounting assembly using a force provided by a hub spring. 
     
     
       14. The method as recited in  claim 11 , wherein at least one ferritic clamp is extended out of the mounting assembly through a pivot motion about a pivot axes. 
     
     
       15. The method as recited in  claim 13 , wherein the pivot motion is created by coupling at least one ferritic clamp to the ferritic hub in a cam configuration such that the pivot motion is generated in response to the displacement of the ferritic hub. 
     
     
       16. The method as recited in  claim 11 , wherein extending the ferritic hub and at least one ferritic clamp further includes extending the ferritic hub and at least one ferritic clamp completely through the central opening of an optical disc. 
     
     
       17. A method of mounting an optical disc to the turntable of an optical disc drive comprising the steps of:
 receiving an inserted optical disc; 
 detecting the presence of an inserted optical disc; 
 generating a disc input signal in response to the presence of an inserted optical disc; 
 generating a magnetic field within the mounting assembly in response to the disc input signal, causing a ferritic hub and at least one ferritic clamp to retract into the mounting assembly; 
 positioning the optical disc such that the optical disc is substantially centered about the turntable central opening; 
 detecting the presence of the optical disc upon being substantially centered on the turntable central opening; 
 generating a disc centered signal in response to the optical disc being substantially centered on the turntable central opening; 
 collapsing the magnetic field in response to the disc centered signal, thereby eliminating the induced magnetic forces applied to the hub and at least one ferritic clamp; and 
 generating an extending force that causes the hub and at least one of the clamps to extend out of the mounting assembly such that the clamp makes contact with the optical disc thereby mounting the optical disc to the turntable. 
 
     
     
       18. The method as recited in  claim 16 , wherein the presence of an inserted optical disc is detected using a sensor. 
     
     
       19. The method as recited in  claim 16 , wherein the presence of the optical disc being substantially centered about the turntable central opening is detected using a sensor. 
     
     
       20. The method as recited in  claim 16 , further comprising the steps of:
 generating a disc detach signal; and, 
 
       generating a second magnetic field event within the mounting assembly in response to the disc detach signal, causing the ferritic hub and at least one ferritic clamp that is in contact with the optical disc to retract into the mounting assembly, thereby detaching the secured optical disc from the turntable. 
     
     
       21. The method as recited in  claim 18 , wherein the disc detach signal is generated through the associated computer of the optical disc drive. 
     
     
       22. A non-transitory computer readable medium for storing a computer program, the computer program executed by a processor for controlling the operation of an optical disc drive comprising:
 computer code for detecting the presence of an inserted optical disc; 
 computer code for generating a disc input signal in response to the presence of an inserted optical disc; 
 computer code for sending the disc input signal to the electromagnet within the mounting assembly; 
 computer code for detecting the presence of the inserted optical disc being substantially centered about the turntable central opening; 
 computer code for generating a disc centered signal in response to the presence of the disc being substantially centered about the turntable central opening; and, 
 computer code for sending the disc centered signal to the electromagnet within the mounting assembly. 
 
     
     
       23. The non-transitory computer readable medium as recited in  claim 21 , wherein the computer program is stored and executed as the firmware of the optical disc drive. 
     
     
       24. The non-transitory computer readable medium as recited in  claim 21 , further comprising:
 computer code for generating a disc detach signal; and, 
 computer code for sending the disc detach signal to the electromagnet within the mounting assembly.

Description:
CROSS REFERENCE TO RELATED APPLICATONS 
     This application claims priority under 35 USC 119(e) to U.S. Provisional Patent Application No. 61/325,301, filed Apr. 17, 2010 and is incorporated herein by reference in its entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The described embodiments relate generally to computing systems and more particularly to an optical disc drive (ODD). 
     BACKGROUND OF THE INVENTION 
     In many cases it is necessary to mount objects onto a turntable. For example, many electronic devices contain an optical disc drive (ODD) for the purpose of reading and writing optical discs. Especially in the design of portable computers and electronic devices, there is a high value placed on reduction of size and weight. Conventional optical disc drives rely upon a coaxial hub/turntable/rotation motor combination that moves substantially along the axis of rotation (the ‘z’ direction) in one direction to allow the optical disc to be inserted and placed on the turntable. In order to secure the optical disc, the coaxial hub/turntable/rotation motor combination must then move in the other direction. This up and down movement in the z direction can substantially add to the overall height (also referred to as the Z stack) of the ODD limiting the potential to reduce the size and/or weight of the ODD and ultimately the electronic device in which the ODD is used. 
     Therefore, what is desired is a reduced Z stack optical disc drive. 
     SUMMARY OF THE DESCRIBED EMBODIMENTS 
     A reduced Z stack height slot loading optical disc drive (ODD) includes at least a slot arranged to receive an optical disc, a turntable having a central opening and a platen arranged to provide a surface upon which the optical disc is secured, and a reduced Z drive mounting assembly used for securing an optical disc to the turntable. The reduced Z drive mounting assembly including a hub assembly having at least a ferritic hub aligned with the turntable central opening and shaped to accommodate an optical disc central hole, an interior surface shaped to act as a cam, a hub spring arranged to generate a spring force used to extend the hub into the turntable central opening in the presence of the optical disc, at least one ferritic securing clamp pivotally attached to the mounting assembly at a pivot point, and an electromagnet arranged to create an induced magnetic field that attracts the ferritic hub and clamp, wherein the magnetic attraction overcomes the spring force and causes the hub and the at least one clamp to retract into the mounting assembly. 
     A method of securing an optical disc to the turntable of an optical disc drive can be performed by retracting a ferritic hub and at least one ferritic clamp into the mounting assembly using magnetic attractive forces generated by an induced magnetic field, centering an optical disc substantially over the turntable central opening, collapsing the induced magnetic field within the mounting assembly, and extending the ferritic hub and at least one ferritic clamp out of the mounting assembly through the turntable central opening such that at least one ferritic clamp makes contact with the optical disc and secures the optical disc to the turntable. 
     A method of mounting an optical disc to the turntable of an optical disc drive can be performed by receiving an inserted optical disc, detecting the presence of an inserted optical disc, generating a disc input signal in response to the presence of an inserted optical disc, generating a magnetic field within the mounting assembly in response to the disc input signal, causing a ferritic hub and at least one ferritic clamp to retract into the mounting assembly, positioning the optical disc such that the optical disc is substantially centered about the turntable central opening, detecting the presence of the optical disc upon being substantially centered around the turntable central opening, generating a disc centered signal in response to the optical disc being substantially centered around the turntable central opening, collapsing the magnetic field in response to the disc centered signal, thereby eliminating the induced magnetic forces applied to the hub and at least one ferritic clamp, and generating an extending force that causes the hub and at least one of the clamps to extend out of the mounting assembly such that the clamp makes contact with the optical disc thereby mounting the optical disc to the turntable. 
     A non-transitory computer readable medium for storing a computer program, the computer program executed by a processor for controlling the operation of an optical disc drive. The computer program including at least computer code for detecting the presence of an inserted optical disc, computer code for generating a disc input signal in response to the presence of an inserted optical disc, computer code for sending the disc input signal to the electromagnet within the mounting assembly, computer code for detecting the presence of the inserted optical disc being substantially centered about the turntable central opening, computer code for generating a disc centered signal in response to the presence of the disc being substantially centered about the turntable central opening, and computer code for sending the disc centered signal to the electromagnet within the mounting assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention and the advantages thereof may best be understood by reference to the following description taken in conjunction with the accompanying drawings. 
         FIG. 1  shows representative computing system in accordance with the described embodiments. 
         FIG. 2  show a cross sectional view of a portion of ODD assembly in a retracted configuration in accordance with the described embodiments. 
         FIG. 3  shows the ODD assembly of  FIG. 2  in an extended configuration. 
         FIG. 4  is a graphical representation showing the relationship between current I EM  in an electromagnet and magneto-motive force  . 
         FIG. 5  shows a top view of the optical disc drive corresponding to the cross sections of optical disc drive shown in  FIGS. 2 and 3 . 
         FIG. 6  shows another embodiment of ODD assembly in a plan view of a slot loading ODD. 
         FIG. 7  is a flowchart detailing process for securing an optical disc to a turntable in accordance with the described embodiments. 
         FIG. 8  shows an alternate embodiment. 
     
    
    
     DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS 
     In the following description, numerous specific details are set forth to provide a thorough understanding of the concepts underlying the described embodiments. It will be apparent, however, to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the underlying concepts. 
     The embodiments herein describe an apparatus and method for a reduced height, slot loading optical disc drive (ODD). The embodiments of the ODD described herein can include any number of configurations having at least an optical disc mounting assembly used to chuck (i.e., secure) an optical disc to a turntable. In one implementation, the optical disc mounting assembly can include a hub formed of at least some magnetic material along the lines of steel. The hub can be configured to move along an axis of rotation of the turntable as well as in a direction perpendicular to a plane of the turntable (referred to as the z direction). The optical disc mounting assembly can also include at least a clamp having a tip integrally formed with a base portion having a shaped surface in contact with a cooperatively shaped surface of the hub. The base portion of the clamp can be pivotally connected to a pivot structure that can be attached to the ODD at, for example, the turntable. In one embodiment, at least some of the clamp can be formed of ferritic material well suited for coupling with an externally applied magnetic field. 
     The optical disc mounting assembly can also include at least one spring or equivalent structure attached directly to the hub. The spring can generate a spring force that can be applied to the hub in a direction that can compel the hub to move outward from the turntable (in the context of this discussion, outward from the turntable can be considered in the +z direction). Since the base portion of the clamp is in cooperative contact with the corresponding surface of the hub, the motion of the hub in the +z direction causes the base portion of the clamp to rotate (i.e., pivot) about the pivot point. The rotation of the base portion, in turn, causes the claw portion and in particular the tip of the clamp to engage the optical disc in a grasping manner securing the optical disc to the turntable with a securing force concomitant with the spring force provided by the spring. In this way, only the tip of the claw portion extends above the optical disc thereby substantially reducing the effective height of the ODD to no more that the extent of the tip above a top surface of a mounted optical disk. 
     The optical disc mounting assembly can also include an electromagnet having at least N electromagnetic coils that can be energized to create a magnetic field. The direction and strength of the magnetic field created by the electromagnetic coil(s) can be influenced by the shape, size, and number of coils as well as the material used to form the electromagnetic coil(s). In this way, by forming at least some of the hub (and in some embodiments, at least some of the clamp) of ferritic material (along the lines of steel), the electromagnet can be used to retract the hub and clamp into the turntable (i.e., move in the −z direction) when the magnetic force is of sufficient strength to overcome the spring force generated by the spring. Moreover, the use of ferritic material to form at least part of the clamp can facilitate the coupling of the clamp with any magnetic field generated by the electromagnet. In this way, the movement of the clamp from the extended position to the retracted position in cooperation with the corresponding surface of the hub can be substantially enhanced. Furthermore, since the electromagnet is not consuming power when the hub/clamp combination is extended and the optical disc is secured to the turntable, overall power consumption of the ODD can be reduced. 
     When an optical disc is inserted into the optical disc drive and the center hole is properly positioned relative to the mounting assembly, a sensor can provide a cut off signal causing power to the electromagnet to be eliminated (or at least reduced below a threshold level). In any case, any magnetic field generated by the electromagnet collapses eliminating any magnetic coupling between the electromagnet and the hub/clamp combination. In this way, the hub is free to move under the influence of the spring force applied by the spring to an extended configuration relative to the turntable. In response to the cam action of the hub on the clamp, the clamp body rotates about the pivot point causing the tip to securely engage the optical disc. 
     These and other embodiments are discussed below with reference to  FIGS. 1-8 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  shows representative computing system  10  in accordance with the described embodiments. Computing system  10  can take the form of a desktop computing system or a portable computing system along the lines of a laptop computer. Accordingly,  FIG. 1  shows computing system  10  in the form of laptop computer  10  having housing  12  formed of upper portion  14  pivotally connected to base portion  16 . Upper portion  14  can include display  18 . When upper portion  14  is moved from a closed position to an open position as shown in  FIG. 1 , upper portion  14  is pivoted with respect to base portion  16  to permit display  18  to present visual content. Laptop computer  10  can include various internal components such as a processor used to process executable instructions stored on various memory devices. The memory devices can include those enclosed within housing  12  such as a main memory that can take the form of a hard disc drive (HDD) or semiconductor memory along the lines of FLASH memory. In addition to memory devices enclosed within housing  12 , external memory devices can be used to augment the memory resources provided by the those memory devices enclosed within housing  12 . Such external memory devices can include memory cards and optical discs such as compact discs (CD) and digital video disc (DVD). In the context of this discussion, focus will be on optical disc memory media and especially with regards to computer systems that utilize an optical disc drive (ODD) enclosed within housing  12 . The ODD can be used to read/write data from/to an optical disc in any form. In order to facilitate the insertion/ejection of the OD from the ODD enclosed within housing  12 , optical disc slot  20  can be formed in housing  12  having a size and shape to accommodate the optical disc. Accordingly, when the optical disc is inserted into slot  20 , the ODD receives and captures the optical disc and as directed by the processor, reads (or writes) data from/to the optical disc. At the completion of the operation or when directed by a user, the ODD ejects the optical disc through slot  20 . 
     The remaining discussion will focus on the optical disc drive. In particular, an optical disc drive having a reduced Z stack height is described. The reduced Z stack height ODD facilitating reducing the overall thickness of computer system  10 . 
       FIG. 2  show a cross sectional view of a portion of ODD assembly  100  in a retracted configuration in accordance with the described embodiments. ODD assembly  100  can include at least turntable  102  on which can be placed an optical disk (OD)  104 . Turntable  102  can rotate about shaft  106  and bushing (or bearing)  108  mounted on base  110 . ODD assembly  100  also can include hub  112  at least partially composed of magnetic material that can rotate about axis of rotation  114  with angular velocity ω. Spring (or springs)  116  attached to hub  112  can exert spring force F spring  directly on hub  112 . Claw (or clamp)  118  can include base portion  120  having surface S 1  in co-operative contact with hub  112  along surface S 2 . Base portion  120  can include pivot pin  122  mounted to pivot structure  124  attached in one embodiment to turntable  102 . ODD assembly  100  can also include electromagnet (EM)  126  having N coils attached to base  110 . EM  126  can generate magnetic field H that can couple with the magnetic material in hub  112 . Various rotational motor elements common in prior art are also shown. The various rotational motor elements can include at least rotation motor electromagnetic coils  128  and cores  130  attached to the base  110  and polarized magnetic material  132  attached to the rim of the turntable  102 . 
     The magnetic coupling between hub  112  and EM  126  can result in attractive magneto-motive force   being applied to hub  112 . Magneto-motive force   can be related to current I EN  flowing through EM  126  according to equation (1):
 
 = N×I   EM   Eq (1)
 
where (as noted above) N is the number of coils in EM  126  and current I EM  is an amount of current that is induced to flow through EM  126 . In this way, spring force F spring  applied to hub  112  by spring  116  can be counterbalanced by inducing current I EM  through EM  126  having a value that is at least equal to I thresh  according to Eq. (2):
 
 F   spring   =N×I   thresh   Eq (2)
 
     In this way, inducing current I EM  that is greater than I thresh  in EM  126  can result in magneto-motive force   sufficient to move hub  112  into the retracted configuration of  FIG. 2 . In some implementations, at least a portion of clamp  118  can also be formed of material capable of magnetically coupling with the magnetic field H generated by EM  126 . In this way, when appropriately energized, EM  126  can act to clear center hole  134  by compelling hub  112  to move in the −z direction. Due to the coupling of magnetic field H and clamp  118 , clamp  118  can also be drawn towards EM  126  resulting in surface S 1  moving in cooperation with surface S 2  of hub  112  as clamp  118  rotates about pivot pin  122 . In this way, a “clear path” can be provided that permits OD  104  to be inserted into ODD assembly  100  and onto turntable  102  during an OD insertion event. On the other hand, sufficiently energizing EM  126  to move hub  112  and clamp  118  from opening  134  can also clear a path for the ejection of OD  104  during an ejection event. Since EM  126  is energized only for that period of time required to insert or eject OD  104  power consumption can be commensurably reduced. 
     De-energizing (by removing I EM  or at least reducing I EM  below I thresh ) EM  126  can result in the collapse of magnetic field H thereby de-coupling EM  126  and hub  112  and/or clamp  118 . In this way, hub  112  can be compelled to move by spring force F spring  in the +z direction from the retracted position of  FIG. 2  to the extended position of  FIG. 3 . It should be noted that as hub  112  moves, clamp tip  136  can enter center hole  134  causing disc  104  to center within hole  134 . Moreover, the cam action provided by the surface S 2  of hub  112  which presses on surface S 1  of clamp  118  can cause the clamp  118  to pivot about pivot  122 . In this way, tips  136  of clamp  118  clamp OD  104  to turntable  102 . It should be noted that tips  136  extend no more than distance “d” above OD  104  thereby limiting the effective Z stack height of ODD  100 . 
       FIG. 4  is a graphical representation showing the relationship between current I EM  in EM  126  and magneto-motive force  . When I EM  is at least equal to I thresh , magneto-motive force   equals spring force F spring  effectively allowing hub  112  and clamp  118  to retract. It should be noted that the net force (F net ) applied to hub  112  and claim  118  is the difference between spring force F spring  and magneto-motive force   (I thresh ). Therefore, release time T release  being an amount of time required for hub  112  and clamp  118  to retract can be controlled by varying current I EM . For example, increasing I EM  can result in a reduction of T release . 
       FIG. 5  shows a top view of ODD  100  where dashed line  202  corresponds to the cross sections of ODD  100  shown in  FIGS. 2 and 3 . As viewed from the top, retractable hub  112  is shown to include at least three clamps  118 . It should be noted, however, that any number of clamps  118  can be used without loss of generality. A portion of the circumference  204  of hub  112  can be used for centering OD  104  on the turntable whereas another portion of the circumference of hub  112  can be configured to accommodate clamp  118  as well as pivot structure  124 . It should be noted that although center hole  136  is shown as being circular, any shape hole can be accommodated without loss of generality. 
       FIG. 6  shows another embodiment of ODD assembly  100  in a plan view of a slot loading ODD  600 . Also shown for context is OD  104  mounted to turntable  102 , optical pickup unit  602  for reading OD  104 , frame  604  that supports optical pickup unit  602  as well as ODD assembly  100 . 
       FIG. 7  is a flowchart detailing process  700  for securing an optical disc to a turntable in accordance with the described embodiments. Process  700  can be carried out by performing at least the following operations. At  702 , a path is cleared for insertion of the optical disk initially by forming a magnetic field by an electromagnet. At  704 , the magnetic field couples the electromagnet and a ferritic portion of a hub and a clamp. The magnetic coupling results in a magneto-motive force being applied to at least the hub and the clamp at  706 . The magneto-motive force, in turn, causes the hub and clamp to move relative to the turntable at  708  so as to remove any portion of the clamp from a central opening of the turntable thereby clearing an insertion path for the optical disc. Next, at  710 , once the insertion path is cleared, the optical disc is centered over the central opening in the turntable causing the electromagnet to de-energize at  712  resulting in the magnetic field collapsing at  714  thereby de-coupling the electromagnet and hub/clamp at  716 . The de-coupling eliminates the magneto-motive force allowing the hub to move in relation to the turntable to an extended configuration at  718 . The clamp moves cooperatively with the hub to extend into the central opening to grasp and secure the optical disc to the turntable at  720 . 
       FIG. 8  shows an implementation of the optical disc drive in the form of ODD  800  where the conventional rotational components (including rotation motor electromagnetic coils  128  and cores  130  attached to the base  110  and polarized magnetic material  132 ) are not included in the retractable hub/retractable claws/turntable combination of  FIGS. 2 and 3 . In the configuration of ODD  800  the motive force for rotation is applied externally to the turntable  102 . For example, the motive force for rotation can be applied to the rim surface  802  of turntable  102 . 
     Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. 
     The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

Metadata:
Filing Date: 20100722
Publication Date: 20120306
Grant Date: 20120306
Priority Date: 20100417
Inventors: WEHRENBERG PAUL J.
Assignee: APPLE INC
CPC Classifications: [{"code": "G11B17/0282", "inventive": true, "first": true, "tree": "[]"}, {"code": "G11B17/0282", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 44789197