Abstract:
One aspect is a detent device with a first hub having an axis and comprising a first feature having both a radial and an axial dimension relative to the hub axis, and having a first hub connection portion. A second hub is located co-axially outside the first hub and comprises a second feature having both a radial and an axial dimension relative to the hub axis, the second feature of the second hub touching the first feature of the first hub when the features are aligned. The second hub has a second hub connection portion. The first and second features have complementary mating geometries. The detent device is configured such that when relative movement is provided to the first and second hub connection portions, a circumferential strain energy of the second hub changes, providing a variable force between the two connection portions depending on their relative position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Non-Provisional Patent Application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/609,604, filed Mar. 12, 2012, entitled “CIRCUMFERENTIAL STRAIN ROTARY DETENT” having Attorney Docket No. R344.142.101, which is herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Detent features are used in commercial products to establish a user experience indicating a home, closed or operating position. Typically, a detent feature and a complementary second detent feature mating with the first detent feature are used to define a type of camming action during their relative movement. Such features do so by providing a holding force in a home position, assuring the user that the device is being used in a proper position. Such features may also provide a “self-closing” force to help the user achieve a home position. Such detent devices may additionally provide protection to the device during exposure to abuse conditions such as transportation shock and vibration. 
         [0003]    Historically, numerous types of loading means have been used between two detent features, among them leaf springs, torsion springs, and compression springs. Often the spring may also serve as one of the two detent features in frictional contact with the other feature. The means of spring loading the first detent feature to the second detent feature allows for both energy storage as well as normal and tangential force loading between the two features. This energy storage and force varies as the device is moved out of one detent position to the next detent position. 
         [0004]    However, these loading devices suffer the drawback of storing energy principally through only one type of deflection: torsional strain (compression springs), or bending strain (torsion springs and leaf springs). As a result, these devices must often be large and bulky to achieve the required energy storage and force required. Reducing the size of these devices while maintaining or increasing the energy and force requirements often results in either excessive stresses which may fatigue and/or break the spring element, or excessive frictional wear between the two detent features which degrades performance and the user experience. 
         [0005]    Many of the current technologies utilize hardened steel to achieve smaller size while accommodating higher stresses and forces, but do so by requiring an oil or grease to lubricate the complementary detent components to avoid galling. 
         [0006]    Many technologies also require more complex assembly methods and a higher number of components. Additionally, other technologies requiring metallic components to ensure reasonable wear and component stresses will have a higher weight, a drawback if weight sensitive components are required, for example, in aircraft. 
         [0007]    For these and other reasons, a need exists for the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. 
           [0009]      FIG. 1  illustrates an exploded perspective view of a detent device in accordance with one embodiment. 
           [0010]      FIG. 2  illustrates a cross-sectional view of a detent device in accordance with one embodiment. 
           [0011]      FIGS. 3   a - 3   b  illustrate cross-sectional views of a rotated detent device in accordance with one embodiment. 
           [0012]      FIG. 3   c  illustrates a torque versus angle relationship for the detent device in accordance with  FIGS. 3   a - 3   b.    
           [0013]      FIG. 4  illustrates an exploded perspective view of a detent device in accordance with one embodiment. 
           [0014]      FIGS. 5   a - 5   d  illustrate partial views of a detent device in accordance with  FIG. 4 , and illustrate alternate complementary geometries. 
           [0015]      FIGS. 6   a - 6   b  illustrate exploded perspective views of detent devices in accordance with alternative embodiments. 
           [0016]      FIG. 7  illustrates a detent device implemented in a hinge design in accordance with one embodiment. 
           [0017]      FIG. 8  illustrates a detent device implemented in a hinge design in accordance with one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
         [0019]    It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise. 
         [0020]      FIG. 1  illustrates detent device  10  in accordance with one embodiment. Detent device  10  includes first hub  20  and second hub  30 . In one embodiment, first and second hubs  20  and  30  are generally cylindrical and first hub  20  is configured to be inserted within second hub  30 . First hub  20  includes first through fourth protruding ridges  21 ,  22 ,  23 , and  24  (ridges  23  and  24  are not visible in  FIG. 1 , but illustrated in  FIG. 2 ) on its outer periphery and second hub  30  includes first through fourth receiving grooves  31 ,  32 ,  33 ,  34  on its inner periphery. In one embodiment, first through fourth protruding ridges  21 ,  22 ,  23 , and  24  are configured to mate with first through fourth receiving grooves  31 ,  32 ,  33 ,  34 . 
         [0021]    In one embodiment, first and second hubs  20  and  30  are configured to rotate relative to each other with first hub  20  within second hub  30 . The relative rotation produces variable torque characteristics that are favorable for many applications. When first through fourth protruding ridges  21 - 24  are mated with first through fourth receiving grooves  31 - 34 , that is, when detent device  10  is in a “home position,” a first force is require to rotate first hub  20  relative to second hub  30 . As ridges  21 - 24  move out of grooves  31 - 34 , a second force higher than the first force is required for relative rotation of first hub  20  within second hub  30 . Once ridges  21 - 24  move away from grooves  31 - 34 , a third force, lower than the second force, but higher than the first force, is required for relative rotation of first hub  20  within second hub  30 . As ridges  21 - 24  then begin to move back into grooves  31 - 34 , a fourth force lower than each of first, second and third forces, is required for relative rotation of first hub  20  within second hub  30 . In one embodiment, fourth force is a relative negative force such that first hub  20  tends to rotate relative to second hub  30  under the influence of the fourth force. 
         [0022]    In one embodiment, second hub  30  is made of engineering plastic that will allow the needed circumferential expansion second hub  30  as ridges  21 - 24  push against second hub  30  as they rotate out of corresponding grooves  31 - 34 . At the same time, the engineering plastic also offers good wear properties for detent device  10 , such that there is no need for lubricant between first and second hubs  20  and  30 . As such, detent device can withstand many thousands of cycles of relative rotation of first hub  20  relative to second hub  30  without significant variations in the applicable forces (first through fourth referred to above) and without lubricant. First hub  20  can be made of either metal or engineering plastic that has good wear properties when in normal contact with second hub  30 . 
         [0023]      FIG. 2  is a cross-sectional view of detent device  10  in accordance with one embodiment. In  FIG. 2 , first through fourth protruding ridges  21 - 24  are mated or aligned with first through fourth receiving grooves  31 - 34  such that detent device  10  is in the home position. In one embodiment, there is a slight interference of protruding ridges  21 - 24  with each of the respective receiving grooves in second hub  30  in order to ensure an adequate holding force in the home position. Clearance is provided between nominal first hub outer surface  25  and nominal second hub inner surface  35  in order to optimize the transition force as first hub  20  rotates relative to second hub  30 . 
         [0024]      FIG. 3   a  illustrates detent device  10  with first hub  20  rotated 45 degrees relative to second hub  30 . As such, first ridge  21  is 45 degrees advanced in a clockwise direction relative to first groove  31 , second ridge  22  is 45 degrees advanced in a clockwise direction relative to second groove  32 , third ridge  23  is 45 degrees advanced in a clockwise direction relative to third groove  33 , and fourth ridge  24  is 45 degrees advanced in a clockwise direction relative to fourth groove  34 . As the protruding ridges  21 - 24  of first hub  20  are forced out of the corresponding receiving grooves  31 - 34  of second hub  30 , second hub  30  both expands circumferentially—creating hoop strain energy—and bends out-of-round between the contacting ridges  21 - 24  of first hub  20 , creating bending strain energy. 
         [0025]    These two elastic strains, circumferential strain and bending strain, serve as a spring function in detent device  10 . The combination of circumferential and bending strain creates an efficient detent mechanism requiring a smaller space than those relying principally on one kind of strain energy. The interference of the protruding ridges  21 - 24  with the inner surface  35  of second hub  30  will determine the frictional force to continue rotating first hub  20  relative to second hub  30  in the condition illustrated in  FIG. 3   a.    
         [0026]    In one embodiment, detent device  10  is configured such that the rotation of first hub  20  and resultant out-of-round bending of second hub  30  causes inner surface  35  of second hub  30  to actually contact outer surface  25  of first hub  20 . Configuring detent device  10  in this manner actually limits the amount of bending strain in second hub  30 , and increases the amount of circumferential strain. By appropriately configuring the physical dimensions of the device, an optimal amount of bending versus circumferential strain may be achieved, creating very efficient energy storage in the detent device without exceeding stress design limits. One skilled in the art will also appreciate that, although inner surface  35  of second hub  30  is illustrated as circular in its home position in  FIG. 2  (apart from the receiving grooves  31 - 34 ), it may be other than circular in shape to achieve the desired optimization of bending and circumferential strain. Similarly, although illustrated as circular, the non-ridge portions of outer surface  25  of first hub  20  could also be other than circular in the home position in alternative embodiments. 
         [0027]    In one embodiment, detent device  10  is configured with relative circumferences for inner surface  35  and outer surface  25  and relative heights for protruding ridges  21 - 24  such that the effective circumferential strain in second hub  30  causes at least 2% strain on the material of second hub  30 . In one embodiment, the material is engineered plastic. In various embodiments, the material of second hub  30  is acetal or nylon. If the material of second hub  30  were a metal, such as hardened steel, a 2% strain on the material would cause the second hub  30  to break after upon repeated cycles of relative rotation of the hubs. Because second hub  30  is engineered plastic, however, this amount of strain provides favorable force characteristics of detent device  10  over many thousands of cycles between the hubs. 
         [0028]    Outer surface  25  defines an effective diameter for first hub  20 . In one embodiment, the height of each of protruding ridges  21 - 24  extending in the radial direction from surface  25  does not exceed 4% of the effective diameter of first hub  20 . This relationship of ridge height to hub diameter also controls the amount of strain on the hub and contributes to the favorable force characteristics of detent device  10  over many thousands of cycles between the hubs. 
         [0029]      FIG. 3   b  also illustrates first hub  20  rotated 45 degrees relative to second hub  30 . In addition, four positional lines are illustrated extending from the center of detent device  30  through discrete positions around the circumference of the device: a first line A intersect approximately the center of first groove  31 ; a second line B intersects approximately an edge of groove  31  (the edge that is on a side closer to groove  32 ); a third line C intersect approximately a midpoint between grooves  31  and  32 ; and a fourth line D intersects approximately an edge of groove  32  (the edge that is on a side closer to groove  31 ). The first line A is repeated intersecting approximately the center of groove  32  illustrating the cyclic nature of detent device  10 . These lines A-D illustrate relative rotational relationships of first and second hubs  20  and  30  throughout 90 degrees, which are then used to illustrate the corresponding force relationships. 
         [0030]      FIG. 3   c  illustrates the force or torque required to move first hub  20  relative to second hub  30  throughout 90 degrees. Using the four positions illustrated in  FIG. 3   b ,  FIG. 3   c  illustrates the required force at each of these approximate positions. 
         [0031]    Position A, that is, the position where each of ridges  21 - 24  are mated with each of grooves  31 - 34  (illustrated in  FIG. 2 ) represents the home position. There is generally a holding force in this position that is dependent on the amount of interference between ridges  21 - 24  of first hub  20  with grooves  31 - 34  of second hub  30 . Moving from this home position generally requires some force, a first force represented generally at the position labeled A on  FIG. 3   c , because this force holds the device in this position. 
         [0032]    Position B, that is, the position where each of ridges  21 - 24  are moving out of each of grooves  31 - 34  represents the initial transition position. The initial transition position represents the movement of first hub  20  out of its home position up to a point of maximum interference with the inner surface  35  of second hub  30 . In one embodiment this represents the maximum force condition, a second force represented generally at the position labeled B on  FIG. 3   c , for detent device  10 . This maximum force is largely governed by the respective dimensions and interference of the ridges  21 - 24  and grooves  31 - 34 . 
         [0033]    Position C, that is, the position where first hub  20  rotated 45 degrees relative to second hub  30  (as illustrated in  FIG. 3   b ) represents the frictional position. The frictional position is a condition where most of the force, a third force represented generally at the position labeled C on  FIG. 3   c , to maintain movement of first hub  20  relative to second hub  30  is frictional, caused by the interference of the protruding ridges  21 - 24  of first hub  20  with the inner surface  35  of second hub  30 . 
         [0034]    Position D, that is, the position where ridges  21 - 24  of first hub  20  are re-entering receiving grooves  31 - 34  of second hub  30 . Depending on the dimensions of ridges  21 - 24  and protrusions  31 - 34 , this fourth force, represented generally at the position labeled D on  FIG. 3   c , may actually be negative before the home position is reached, causing first hub  20  to “self-rotate” unless a restraining (negative) force is applied to prevent such motion. 
         [0035]    In one embodiment, detent device  10  provides a force versus angle relationship that is useful in a variety of applications. Furthermore, configuring the circumference of outer surface  25  of first hub  20  relative to the circumference of inner surface  35  of second hub  30  provides control of both circumferential strain and bending strain of second hub  30 . This provides favorable spring function in detent device  10  allowing an efficient device requiring a relatively small space. Configuring second hub  35  of an engineered plastic further allows a detent device  10  that is free of any kind of lubrication. This simplifies the design, yet provides thousands of cycles of relative rotation of first and second hubs  20  and  30  while maintaining a substantially consistent force versus angle relationship over these thousands of cycles. 
         [0036]      FIG. 4  illustrates detent device  50  in accordance with one embodiment. Detent device  50  includes first hub  60  and second hub  70 , and in one embodiment, first and second hubs  60  and  70  are generally cylindrical with first hub  60  configured to be inserted within second hub  70 . First hub  60  includes first through fourth receiving grooves  61 ,  62 ,  63 , and  64  (grooves  63  and  64  are not visible in  FIG. 4 ) on its outer surface  65  and second hub  70  includes first through fourth protruding ridges  71 ,  72 ,  73 , and  74  on its inner surface  75 . In one embodiment, first through fourth receiving grooves  61 ,  62 ,  63 , and  64  are configured to mate with first through fourth protruding ridges  71 ,  72 ,  73 , and  74 . 
         [0037]    Detent device  50  operates similarly to detent device  10  as described above, but with protruding ridges  71 ,  72 ,  73 , and  74  and receiving grooves  61 ,  62 ,  63 , and  64  reversed relative to inner surface  75  of second hub  70  and outer surface  65  of first hub  60 . Second hub  70  must still allow for circumferential expansion, so its preferred material is a wear resistant engineering plastic, such as acetal or nylon. Also, the circumference of outer surface  65  of first hub  60  is still configured relative to the circumference of inner surface  75  of second hub  70  to control and limit both circumferential strain and bending strain of second hub  70  to provide favorable spring function in a relatively small space. 
         [0038]    Just as reversing the ridges and grooves between first hubs  20 / 60  and second hubs  30 / 70  retains the essential detent function from circumferential tensile strain of second hub  70  ( FIG. 4 ), one skilled in the art will understand that configuring first hubs  20 / 60  of a more compliant material than second hub  30 / 70  will result in circumferential compressive strain of first hub  20 / 60 , achieving the same detent function. 
         [0039]    In both detent devices  10  and  50 , outer surface  25 / 65  of first hub  20 / 60  and inner surface  35 / 75  of second hub  30 / 70  are illustrated as having commentary mating geometries. By “complementary mating geometries” of the two detent surfaces—protruding ridges  21 / 71 ,  22 / 72 ,  23 / 73 , and  24 / 74  and receiving grooves  31 / 61 ,  32 / 62 ,  33 / 63 , and  34 / 64  in the illustrated embodiments—it is meant that the surfaces are functionally complementary, and that one feature moves radially inward towards the other when the two features are aligned (home position), allowing second hub  30 / 70  to relax its circumferential expansion and lower the normal force between the two features. In other words, a protruding ridge moves at least partway into a receiving groove (or the opposite, depending on which hub has which feature). 
         [0040]      FIGS. 5   a - 5   d  illustrate embodiments of various complementary mating geometries for first ridge  71  and first grove  61  from detent device  50 .  FIG. 5   a  illustrates first ridge  71   a  and first grove  61   a  with geometries that are substantially dimensionally equivalent, such that when it the home position first ridge  71  and first grove  61  share an adjacent border.  FIGS. 5   b - 5   d  illustrate alternate complementary mating geometries for first ridge  71   b/c/d  and first grove  61   b/c/d  that are not dimensionally equivalent, but that achieve the same functional result. One skilled in the art of cam design will understand that normal design methodologies are used to determine the profiles of the protruding ridges and receiving grooves in a manner that results in desirable and allowable forces, energy storage, contact stresses, and wear. 
         [0041]    Detent devices  10  and  50  are illustrated with four protruding ridges and four receiving grooves spaced substantially equidistant around the respective perimeters of the hubs. Other embodiments can use less protrusions and complementary grooves, for example one, two or three. Furthermore, larger numbers of protrusions and complementary grooves can be used. Also, the spacing between the pairs of protrusions and complementary grooves can be varied around the circumference of the hubs dependent on the desired performance characteristics of the detent device. 
         [0042]      FIG. 6   a  illustrates detent device  90  in accordance with one embodiment. Detent device  90  includes first hub  100  and second hub  110 . First hub  100  includes first hub main portion  106  and first hub connection portion  108  and second hub  110  includes second hub main portion  116  and second hub connection portion  118 . In one embodiment, first and second hub main portions  106  and  116  are generally cylindrical with first hub main portion  106  configured to be inserted within second hub main portion  116 , thereby providing a detent device with operational characteristics consistent with that described above with respect to devices  10  and  50 . 
         [0043]    First hub main portion  106  includes first through fourth protruding ridges  101 ,  102 ,  103 , and  104  (ridges  103  and  104  are not visible in  FIG. 6   a ) on its outer surface and second hub main portion  116  includes first through fourth receiving grooves  111 ,  112 ,  113 , and  114  on its inner surface. In one embodiment, first through fourth receiving grooves  111 ,  112 ,  113 , and  114  are configured to mate with first through fourth protruding ridges  101 ,  102 ,  103 , and  104 . 
         [0044]    In one embodiment, first and second hub connection portions  108  and  118  facilitate the circumferential expansion of first and second hubs  100  and  110  and allow connection of detent device  90  into further mechanism, such as hinges. First and second hub connection portions  108  and  118  can be readily coupled to other devices, such as hinge devices, for controlled relative rotations providing force versus angle characteristics similar to that illustrated in  FIG. 3   c  due to the interaction of first hub main portion  106  and second hub main portion  116 . 
         [0045]      FIG. 6   b  illustrates detent device  130  in accordance with one embodiment. Detent device  130  includes first hub  140  and second hub  150 . First hub  140  includes first hub main portion  146  and first hub connection portion  148  and second hub  150  includes second hub main portion  166  and second hub connection portion  168 . In one embodiment, first and second hub main portions  146  and  166  are generally cylindrical with first hub main portion  146  configured to be inserted within second hub main portion  166 , thereby providing a detent device with operational characteristics consistent with that described above with respect to devices  10  and  50 . 
         [0046]    First hub main portion  146  includes first through fourth protruding ridges  141 ,  142 ,  143 , and  144  on its outer surface and second hub main portion  166  includes first through fourth receiving grooves  151 ,  152 ,  153 , and  154  on its inner surface. In one embodiment, first through fourth receiving grooves  141 ,  142 ,  143 , and  144  are configured to mate with first through fourth protruding ridges  151 ,  152 ,  153 , and  154 . 
         [0047]    In one embodiment, first and second hub connection portions  148  and  168  facilitate the radial expansion of first and second hubs  140  and  150  and allow connection of detent device  130  into further mechanism, such as hinges. First hub main portion  146  is expanded axially relative to second hub main portion  166 , such that once first hub main portion  146  is inserted into second hub main portion  166 , a section of first hub main portion  146  that is coupled to first hub connection portion  148  extends outside second hub main portion  166  such that there is no interference between second hub main portion  166  and first hub connection portion  148 . In this way, first and second hub connection portions  148  and  168  can be readily coupled to other devices, such as hinge devices, for controlled relative rotations. 
         [0048]    Embodiments, such as illustrated for detent devices  10 ,  50 ,  90  and  130 , provide controlled relative rotation having force versus angle characteristics similar to that illustrated in  FIG. 3   c . These detent devices are light weight with utilization of engineering plastics for the hubs. Furthermore, these devices are lubricant free, yet able to provide repeatable torque over many thousands of cycles of relative rotation of the hubs. The devices are spatially efficient through the storage of energy by circumferential as well as bending strain. The detent devices are easy to assemble and contain a minimum number of parts. 
         [0049]      FIG. 7  illustrates a partially exploded view of detent hinge  170  in accordance with one embodiment. In one embodiment, detent hinge  170  illustrates a practical implementation of two detent devices, such as detent device  10  described above. Detent hinge  170  includes first, second, and third hinge sections  180 ,  190  and  200 . First hinge section  180  includes first connection  184  and first receiving hub  182 . Second hinge section  190  includes second connection  196 , first extending hub  194 , and second extending hub  192 . Third hinge section  200  includes third connection  204  and second receiving hub  202 . 
         [0050]    When assembled, first extending hub  194  of second hinge section  190  is inserted in first receiving hub  182  of first hinge section  180 . In one embodiment, first extending hub  194  includes a plurality of ridges and first receiving hub  182  includes a plurality of receiving grooves configured to mate with the ridges, similar to that described above with the various detent devices. Similarly, second extending hub  192  of second hinge section  190  is inserted in second receiving hub  202  of third hinge section  200 . In one embodiment, second extending hub  192  includes a plurality of ridges and second receiving hub  202  includes a plurality of receiving grooves configured to mate with the ridges, similar to that described above with the various detent devices. Furthermore, first and second receiving hubs  182  and  202  are configured to circumferentially expand, thereby providing both circumferential and bending strain. 
         [0051]    In operation, first, second, and third hinge sections  180 ,  190  and  200  are coupled to two or more bodies for relative rotation. For example, second connection  196  can be mounted to a base of a laptop computer, while first connection  184  and third connection  204  are coupled to a screen of the laptop computer. This allows the screen of the computer to rotate relative to the base under the force influence of the two detent devices formed from the combination of first receiving hub  182  of first hinge section  180  rotating about first extending hub  194  of second hinge section  190  and second receiving hub  202  of third hinge section  200  rotating about second extending hub  192  of second hinge section  190 . The torque profile in one embodiment is similar to that given in  FIG. 3   c.    
         [0052]    In one embodiment, first, second, and third hinge sections  180 ,  190  and  200  can be mounted to three different rotatable bodies. For example, second connection  196  can be mounted to a base, while first and third hinge sections  180  and  200  are respectively each mounted to first and second rotatable bodies. As such, the first body is rotatable relative to the base under the influence of the detent device formed from first receiving hub  182  of first hinge section  180  rotating about first extending hub  194  of second hinge section  190 . The second body is rotatable relative to the base under the influence of the detent device formed from second receiving hub  202  of third hinge section  200  rotating about second extending hub  192  of second hinge section  190 . 
         [0053]      FIG. 8  illustrates detent friction hinge  210  in accordance with one embodiment. Detent friction hinge combines a detent device, such as described above with respect to detent devices  10  and  50 , with a friction hinge, that is, a constant torque clutch, in order to achieve a higher and more controlled friction between detent positions. In one embodiment, detent friction hinge  210  includes first hinge portion  212 , second hinge portion  218 , first hub  214  and second hub  216 . First hinge portion  212  is mounted to a first hinged body and second hinge portion  218  is mounted to a second hinged body, such that the first and second hinges bodies can be rotated relative to each other under the control of detent friction hinge  210 . 
         [0054]    In one embodiment, a plurality of frictional elements  220  are provided between first hinge portion  212  and second hinge portion  218  to provide a frictional rotational force therebetween (in  FIG. 8 , a portion of second hinge portion  218  is cut away to partially reveal frictional elements  220 ). In addition, first hub  214  in configured with protruding ridges and second hub  216  is configured with grooves to form complementary mating geometries. As the first and second hinges bodies are rotated relative to each other, detent friction hinge  210  creates resistance to rotation from frictional elements  220  between first hinge portion  212  and second hinge portion  218 , as well as from the resistance of the protruding ridges of first hub  214  with the receiving grooves of second hub  216 . Frictional elements  220  essentially work in series with the detent device created by first and second hubs  214  and  216 . 
         [0055]    In one embodiment, detent friction hinge  210  accordingly provides controlled friction between detent positions, while providing a user with a sense of reaching a desired home position, a reduction of force during this final movement, and a firm holding force once in the home position. 
         [0056]    Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.