Abstract:
Various embodiments for magnetic detent assemblies provide for detent devices with improved performance and manufacturability. In one embodiment, magnetic detent assemblies provide for custom detent positions and custom force profiles by including a pair of unitary magnetic components each having a special geometry. In an embodiment, the changing area of overlap (and hence magnetic flux) between the magnetic components can give rise to the custom detent positions and custom force profiles. In a specific embodiment, the magnetic components can comprise an N-point star shaped geometry, where the number and distribution of the start wings can be varied to define customized detent positions and the contour of the star wings can be varied to create customized force profiles. In other embodiments, devices such as laptop computers and docking stations for handheld electronic devices can implement multi-position detent hinges with the magnetic detent assemblies.

Description:
BACKGROUND OF THE INVENTION 
     A detent is a catch or a lever mechanism that defines resting positions as one part of an assembly moves relative to another part. Conventional detent devices typically rely on mechanical means, such as a lever and socket combination, to restrict the movement of the system in defining the resting positions. One type of detent is a rotational device that divides the rotation of a wheel, shaft or hinge into discreet increments where the fixed discreet increments define the detent positions. These mechanical systems commonly employ a small gravity or spring actuated lever paired with a notched shaft to help define the detent positions. 
     In addition to defining detent positions, some detent devices offer self-centering forces that help to align and move the detent bodies into detent positions when the detent bodies are perturbed from their detent positions. In mechanical detents, centering mechanisms can include a wide diversity of contraptions including springs, levers, balls, etc. As a rotating mechanism is rotated to misalign two detent bodies from a detent position, a self-centering force will arise to slow the rotation and position the rotating detent bodies back into alignment. When a perturbing force is large enough to overcome the self-centering force to move a body completely out of the force field of a first detent position, another self-centering force will arise to place the bodies into another, typically adjacent, detent position force field, thereby moving the bodies into the other detent position. 
     Existing detent mechanisms therefore typically require two bodies with surfaces that slide against each other. Friction between these two surfaces and other environmental effects cause the force profile offered by the detents to change over time. This may result in less than optimum performance as the device wears. Because these types of detent devices also involve multiple parts such as shafts, sockets, levers, springs, etc., tolerance requirements can also add to the complexity and cost of the device manufacture and assembly. There is therefore a need for detent systems with improved performance and manufacturability. 
     BRIEF SUMMARY OF THE INVENTION 
     Various embodiments of the present invention are directed at detent systems using magnetic components. In one embodiment, the present invention may provide a robust magnetic assembly that employs a single magnetic component per body. In the single magnet embodiment, instead of using a plurality of components, a single magnetic component in each body of the detent mechanism may feature a customized geometry that creates a customized set of detent positions and/or force profiles. The single magnet detent system of the present invention can require fewer parts and can therefore be easier and more cost-effective to manufacture. A single unitary piece of magnet, for example, may be easier to mold and manufacture than a plurality of separate parts that have to be subsequently assembled with specific tolerances. 
     Accordingly, in one embodiment, the present invention may include a magnetic detent assembly having a first body and a second body, with each of the first body and the second body having a magnetic component characterized by a special geometry wherein an area of overlap between the first body and the second body is varied as the bodies move relative to each other. The change in the magnetic flux passing between the first body and the second body as they move relative to each other may give rise to a plurality of detent positions. Depending on the specific embodiments, either the plurality of positions with local minimums of magnetic fluxes or the plurality of positions with local maximums of magnetic fluxes can be made to define the plurality of detent positions. The magnetic components can be made of materials such as magnetic, ferromagnetic, or ferrous materials. In an alternative embodiment, the magnetic components may further comprise electromagnetic components. 
     In another embodiment, the magnetic components can be made to include a pair of matched geometries. The term matched geometries as used herein is not limited to geometries that have identical shape (i.e. identical contour and size), but can also include geometries with dissimilar shapes. In a specific embodiment, the pair of matched geometries may comprise a single N-point star shape, where the number of protrusions or wings N can be varied to define N number of detent positions. In a further embodiment, the contour of the N-point star shape magnetic components may be modified to produce a customized force profile. The N-point star shape may be used in a detent where the first body and the second body are designed to rotate with respect to each other. In another embodiment, the N-point star shape detent may be adapted for use in a hinge system. In another embodiment, the N-point star shape detent can also be adapted for use in a sealed system where the sealed system may be waterproof, dustproof, or both. 
     In a specific embodiment, the magnetic components of a magnetic detent assembly can be adapted not just to create customized detent positions and customized force profiles, but also to hold a first detent body in close proximity to a second detent body. In an alternative embodiment, mechanical means can be used to hold the first detent body and the second detent body in close proximity. 
     In a specific embodiment, the first and second detent bodies of a detent assembly can include magnetic components that are adapted to move along certain predefined dimensions. In one specific embodiment, the detent bodies can be adapted to move relative to each other along one linear dimension. In another specific embodiment, the detent bodies can also be adapted to move relative to each other along a single axis of rotation. Where the detent bodies are adapted to move relative to each other along a single axis of rotation, for example, the detent assembly can be further adapted to be part of a hinge. 
     A better understanding of the nature and advantages of the present invention can be gained by reference to the detailed description below and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a general detent assembly. 
         FIG. 2  illustrates a simplified view of a linear, single dimension-based magnetic detent in accordance with one embodiment of the invention. 
         FIG. 3  illustrates a simplified view of a rotation-based magnetic detent in accordance with one embodiment of the invention. 
         FIG. 4  illustrates a side view of a rotation-based magnetic detent showing an example of magnet orientation in accordance with one embodiment of the invention. 
         FIG. 5  illustrates a magnetic detent structure that provides customized detent positions in accordance with one embodiment of the invention. 
         FIG. 6  illustrates a magnetic detent structure that provides for detent forces in accordance with one embodiment of the invention. 
         FIG. 7  illustrates a magnetic detent structure that provides for customized detent forces in accordance with one embodiment of the invention. 
         FIG. 8  shows an exemplary laptop computer that employs a magnetic detent at its hinge in accordance with one embodiment of the invention. 
         FIG. 9  illustrates an exemplary media player docking device that employs a magnetic detent providing for multiple detent positions for the docked media player in accordance with one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed at magnetic detents and systems employing magnetic detents.  FIG. 1  illustrates the general principle of a magnetic detent. Depicted in  FIG. 1  is detent  100  comprising a first body  101  and second body  102 . In this example, first detent body  101  and second detent body  102  are adapted to rotate about a common axis of rotation  105 .  FIG. 1  depicts detent  100  in two detent positions  103  and  104 . When detent bodies  101  and  102  are in one of the two detent positions, they are in a configuration of relative stability with respect to each other. Depending on the strength of magnetic forces holding detent body  101  and detent body  102  in a detent position, a small perturbation of an external force on either bodies may not move the detent bodies out of a detent position. If a small enough force is applied, a self-aligning force will arise to move the detent bodies  101  and  102  back to the initial detent position. A larger perturbation of an external force on either body may however overcome the self-aligning force to move the bodies out of the initial detent position. In the example shown in  FIG. 1 , if detent positions  103  and  104  are the only detent positions provided by detent  100 , an application of a large external force will move the detent bodies successively between detent positions  103  and  104 . 
       FIG. 2  shows a simplified view of a linear, single dimension-based magnetic detent in accordance with one embodiment of the invention. As can be seen in this exemplary embodiment, the magnetic detent may comprise two magnetic components  201  and  202  featuring predefined geometries that match. In the specific embodiment, the pair of geometries comprises a flat linear shape with four bulges, defining a set of overlapping areas as the pair is moved along each other. In this embodiment, as well as throughout this application, the term magnetic component may refer to a component comprising either a permanent magnet or a ferromagnetic or ferrous material or a magnetic component comprising electromagnetic subcomponents. In the embodiment of  FIG. 2 , each of the magnetic components may be made of a magnetic material and may include a top portion A and a bottom portion B, as indicated by the different shadings. The inset shows, in accordance with the embodiment, that the top portion A, corresponding to portions  201 A and  202 A of magnetic components  201  and  202 , respectively, may represent a north pole of the magnetic components. The bottom portion B, corresponding to portions  201 B and  202 B of magnetic components  201  and  202 , respectively, may correspond to a south pole of the magnetic components. In accordance with another aspect of this embodiment, each of the magnetic components  201  and  202  may also be characterized by four bulges  203 ,  204 ,  205 , and  206  that can define four detent positions. The number of bulges in the embodiment of  FIG. 2  is illustrative only and can be varied depending on the application. 
     In the embodiment shown in  FIG. 2 , because of the pole arrangements of components  201  and  202 , the position where the overlap of the magnetic flux between components  201  and  202  is at a maximum may also define a position of maximum relative stability between the two detent bodies. The initial position where all four bulges overlap and line up may thus represent a dominant detent position. As magnetic component  201  moves in the direction of the arrow over magnetic component  202 , the overlap of the magnetic flux decreases, placing the magnetic detent into a configuration of relative instability. As magnetic component  201  moves further along the direction of the arrow, however, the bulges of magnetic components  201  and  202  may line up again, increasing the overlap of magnetic flux, placing the magnetic detent back into a configuration of relative stability again. This second detent position may be less dominant than the first because only three bulges line up. The amount of perturbation force needed to move the assembly out of this second detent position may be less than that required for the initial detent position. 
       FIG. 3  shows a simplified view of rotating magnetic detent  300  in accordance with another embodiment of the invention. As illustrated, magnetic detent  300  comprises a first detent body  301  having magnetic component  303  and second detent body  302  having magnetic component  304 . In one embodiment, magnetic components  303  and  304  may be made up of a magnetic, ferromagnetic, or ferrous material. In a further embodiment, magnetic component  303  may be made of a permanent magnetic material, and magnetic component  304  may include an attraction plate made of a ferromagnetic material such as steel. In yet another embodiment, at least one of the magnetic components may be made of an electromagnetic subcomponent where the magnetic flux can be turned on and off with the application of electric power. 
     In the embodiment of  FIG. 3 , magnetic components  303  and  304  may feature a unitary N-point star geometry, the N points indicating the number of “wings” in the N-point star geometry, where the number N and the shape of the wings can be varied to define a set of customized detent positions and force profiles. The number of wings may define the number of detent positions magnetic components  303  and  304  may encounter as detent bodies  301  and  302  are rotated about each other. A larger number of wings may provide more detent positions while a fewer number of wings may result in fewer detent positions.  FIG. 4  illustrates a side profile of the magnetic fields in relation to the magnetic components of the N-point star geometry. 
     Depending on the shape and contour of the wings, as detent bodies  301  and  302  are rotated about each other, the profile of self-centering forces magnetic components  303  and  304  will encounter as they repel and attract each other can also be customized. In a specific embodiment, the design of a pair of custom matched geometries may be obtained first by determining the custom force profile needed, second by designing a sequences of areas of overlaps that would give rise to the required custom force profile, and third by creating a pair of matched unitary geometries (one for each of the complementary magnetic components) that would give rise to the sequences of areas of overlaps as the two detent bodies are moved relative to each other. In general, the pair of matched geometries may or may not be the same. In the embodiment shown in  FIG. 3 , the pair of matched geometries are the same—both defined by a unitary N-point star geometry. 
       FIG. 5  depicts in more detail magnetic detent bodies with an exemplary 5-point star shaped geometry featuring five detent positions in accordance with an illustrative embodiment of the current invention. Depicted is a top-down perspective of magnetic detent  300  in configurations  501  and  502 . In configuration  501 , magnetic components  303  and  304  are aligned with each other. In configuration  502 , magnetic components  303  and  304  are misaligned with respect to each other. In one embodiment, where magnetic component  303  can be made of a permanent magnet and magnetic component  304  can be made of an attraction plate of ferrous material, configuration  501  may define a configuration of relative stability while configuration  502  defines a configuration of relative instability. The configuration of relative stability may define five detent positions associated with detent  300 . As detent bodies  301  and  302  are rotated with respect to each other about axis  105 , the overlap of the magnetic fluxes between components  303  and  304  may reach a maxima in configuration  501  and a minima in configuration  502 . Configuration  501  thus may represents five maxima positions spaced 72° apart from each other symmetrically around the axis of rotation  105 . The symmetric geometry of the 5-point star shape may thus provides five symmetric, equivalent detent positions spread 72° around common axis of rotation  105 . In one embodiment, the attraction forces between magnetic components  303  and  304  may be such that a small perturbation of an external force will not move detent bodies  301  and  302  out of detent configuration  501 . A self-aligning force will realign detent bodies  301  and  302  back to detent configuration  501 . 
     Configuration  502  represents five positions where the overlap of magnetic flux between  303  and  304  are minimal, corresponding to five positions of instability spaced 72° apart from each other symmetrically around the axis of rotation  105 .  FIG. 6  shows a magnetic detent that provides for customized detent positions in more detail. In the configuration shown in  FIG. 6 , the overlap of magnetic flux between magnetic components  303  and  304  is at a minimum, defining a position of relative instability. In one preferred embodiment, configuration  502  can be considered to be force barriers separating detent positions defined by configuration  501 . If a perturbing force is small, the magnetic forces that arise between magnetic components  303  and  304  will place the detent back into configuration  501 . If a perturbing force is large enough, the magnetic forces that arise between magnetic components  303  and  304  will not be strong enough to place the detent back into an initial detent position. 
       FIG. 7  illustrates an exemplary implementation of a magnetic detent that provides for a customized detent force profile in addition to providing for a customized set of detent positions in accordance with an embodiment of the invention. Depicted are top down perspectives of a magnetic detent  700  in two stable configurations  701  and  703  and one unstable configuration  702 . In a specific embodiment, a customized force profile is implemented by adding an extension to one or more wings of star-shaped magnetic components  303  and  304 . The resulting elongated wings  303   e  and  304   e  of magnetic components  303  and  304  create an asymmetrical star-shaped geometry. In such an embodiment, configuration  701  may represent the most stable configuration as magnetic detent bodies  301  and  302  are rotated about axis of rotation  105 . In configuration  701 , not only are the protrusions or wings of magnetic components  303  and  304  aligned, but their respective elongated portions or extensions  303   e  and  304   e  are also aligned, creating a maximal overlap of magnetic fluxes between components  303  and  304 . As magnetic detent  700  is rotated, components  303  and  304  may become un-aligned and enter a configuration of relative instability  702 . If an external force is small enough and is removed, a self-aligning force will move detent bodies  301  and  302  back into configuration  701 . Continuing with the rotation, detent bodies  301  and  302  eventually enter into another detent position  703 . However, because elongated portions  303   e  and  304   e  of asymmetrical star-shaped magnetic components  303  and  304  are no longer aligned, the overlap of the magnetic fluxes between components  303  and  304  while greater than that of configuration  702  will be less than that associated with configuration  701 , potentially rendering detent configuration  703  stable but not as stable as configuration  701 . The result is an asymmetric force profile where the force needed to move a detent in configuration  701  out of position will be greater than that needed to move a detent in configuration  703  out of position. 
     The extension of a wing is but one way to render the embodiment of the N-point star geometry asymmetric. For example, another method is to change the angles separating the wings of an N-point star geometry. In an embodiment, instead of 5 wings equally spaced at 72° apart, a geometry may have a pair of wings are separated at 40° apart and another pair separated 104° degrees apart. The total number of angles separating the 5 wings remains the same at 360° as the symmetric geometry. For example, instead of 5 angles of 72°, the asymmetric geometry has 3 angles of 72°, 1 of 40°, and 1 of 104°. 
     The general principles described in connection with the illustrative embodiment shown in  FIGS. 6 and 7  can be applied to magnetic detents using a variety of shapes. That is, other geometries can also be used to provide for a dominant detent position among a plurality of other less dominant detent positions. In the embodiment shown in  FIG. 6 , a customized symmetric position profile can arise because the five wings of the 5-point star geometry (and hence detent positions) are distributed symmetrically, at 72° apart, about the axis of rotation. A customized asymmetric force profile may be implemented in the embodiment shown in  FIG. 7  by adding extensions that create asymmetric profiles for the wings. Examples of other geometries might include for example, propeller shaped, oval shaped, square shaped, or crossed shaped geometries. 
     In another embodiment, the detent assembly can employ electromagnetic subcomponents whereby the number of detent positions and/or the selection of one or more dominant detent positions can be controlled electronically. According to this embodiment, the shape of each electromagnetic subcomponent may be designed such that portions of the subcomponent (e.g., one or more wings or one or more extensions of the wings) can be electronically energized (i.e. magnetized or demagnetized). According to one embodiment, in a detent assembly with a electromagnetic subcomponent, a control circuit can be coupled to the component to allow, for example, a user to adjust the number of detent positions and/or one or more preferred detent positions that are more dominant than other detent positions. 
     A customized force profile may also be the basis of a customized tactile feel to a magnetic detent. Referring to the embodiment shown in  FIG. 7 , as detent bodies  301  and  302  are moved 72° from configuration  701  to configuration  703 , a self-aligning force biased toward moving the detent bodies back into configuration  701  may arise for most of the interval between configurations  701  and  703 . At the midpoint (36°) between configurations  701  and  703 , the self-aligning force may continue to be biased toward the more stable configuration  701  because configuration  701  is more stable than configuration  703 . At some point past 36° between configurations  701  and  703 , a point that depend on the precise geometries associated with the magnetic components  303  and  304 , a self-aligning force will eventually arise to bias the magnetic detent toward moving detent bodies  303  and  304  to configuration  703 . This unique profile of self-centering force profiles can be leveraged to create customized tactile feels for magnetic detents. The enlargement of a bulge or wing among others is but one approach to customizing force profiles in accordance with a specific embodiment of the current invention. Other approaches are also possible. 
     In other embodiments, the present invention provides devices and systems that incorporate magnetic detents. Two examples of such devices are described in connection with  FIGS. 8 and 9 .  FIG. 8  shows laptop computer  800  with hinge  802  that employs magnetic detent  804  in accordance with one embodiment of the invention. In one specific embodiment, detent hinge  802  may be customized to provide for a predetermined set of angles at which the laptop screen can be most ergonomically displayed. In another specific embodiment, detent hinge  802  may also be customized to provide for a dominant detent position corresponding to a recommended viewing angle of the laptop screen. A variation of this embodiment may employ electromagnets in detent assembly  804  wherein the geometric asymmetries (e.g., extensions  303   e  and  304   e  in  FIG. 6 ) can be electrically activated or deactivated to allow for the dominant detent position to be electrically set. In yet another embodiment, detent hinge  802  may also be customized to provide for customized tactile response when desired. 
       FIG. 9  illustrates docking station  900  for hand-held electronic device  902  (e.g., a media player) that employs a magnetic detent in accordance with one embodiment of the invention. According to this embodiment, docking station  900  may include connector  904  that receives device  902 . Connector  904  may be affixed to a board inside the body of docking station  900  by a hinge assembly that includes magnetic detent  906 . Detent hinge  906  may be customized to provide for a predetermined set of angles relative to base  908  at which a user interface of device  902  can be most ergonomically displayed and used. Similar to variations discussed in connection with the laptop hinge of  FIG. 8 , detent hinge  906  can also be customized to provide for a dominant detent position corresponding to the best viewing angle of the player UI. An electromagnetic embodiment of detent hinge  906  allows the detent to be turned off and on according to one embodiment of the invention. An electromagnetic embodiment of detent hinge  906  may allow for selecting the dominant position electronically. In yet another preferred embodiment, the detent hinge may be adapted to provide for customized tactile response when adjusting the angle of docked device  902 . 
     In conclusion, the present invention provides various embodiments for magnetic detents and for implementing devices and systems employing magnetic detents. While these inventions have been described in the context of the above specific embodiments, modifications and variations are possible. For example, detent assemblies according to the present invention can be held together only by magnetic attraction force or a combination of magnetic and mechanical means. Also, references to various types of materials are for illustrative purpose and other similar alternatives may also fall within the scope of the present invention. Similarly, shapes, dimensions, angles and sizes provided throughout the above description are for illustrative purposes only, and the inventive concepts described herein can be applied to structures with different dimensions. Other examples of applications of magnetic detents exist and will be readily recognized by a person of skill in the art. Accordingly, the scope and breadth of the present invention should not be limited by the specific embodiments described above and should instead be determined by the following claims and their full extend of equivalents.