Abstract:
The housing ( 12 ) for a portable device ( 10 ) has a cavity ( 40 ) which engages a boss ( 28 ) on a U-shaped clip ( 22 ) to prevent a relative rotation between the housing ( 12 ) and the U-shaped clip ( 22 ) whenever a force is exerted on the free end of the U-shaped clip ( 22 ) when fitted over a belt. The boss ( 28 ) is disengaged from the cavity ( 40 ) whenever a force is applied which deforms the U-shaped clip ( 22 ), thereby allowing the housing ( 12 ) to be rotated to view an annunciator presenting a message. 
     The U-shaped clip ( 22 ) rotates about a pivot formed by a first boss ( 26 ), and second boss ( 24 ) having a D-shape, which engage a first bearing ( 42 ) and second bearing ( 44 ), respectively. The D-shape of the second boss ( 24 ) and configuration of the second bearing ( 44 ) enable the U-shaped clip ( 22 ) to be assembled to/disassembled from the housing ( 12 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of belt clips for portable devices, and more particularly to a latching mechanism for a rotating belt clip for a portable, belt worn device. 
     BACKGROUND OF THE INVENTION 
     Belt clips have been provided on many devices so that the devices can be conveniently carried by the person using the device. This is especially true of electronic devices such as pagers, cellular telephones, and numerous other electronic devices. Most prior art belt clips are more or less permanently affixed to the device housing, and often require special tooling to assemble the belt clip to the device housing. Some prior art belt clips have been designed to allow the belt clips to be easily assembled to the device housing when the device is to be carried on the belt or in a pocket by the person using the device. Such belt clips were often easily removed from the device housing, thereby providing a “clipless” devices which were often more conveniently carried in a pocket. 
     Many devices which are carried on the belt were provided with displays which were used to display information which was received. In many instances, such displays were not always located on the top of the device, but rather were located on the front surface of the device. When a message was to be viewed in such a device, the device generally had to be removed from the belt so as to enable the person using the device to view the message. To alleviate the problem of removing the device from the belt, various prior art holsters were designed which allowed the device to easily removed, or be rotated into a position such that the display could be viewed. While holsters which allowed the device to be removed or rotated resolved the problem of viewing the display, such holsters often added significant cost and were often lost. 
     What is needed therefore is a belt clip which can be easily assembled to the device housing, and which allows the device to be rotated so that the display can be easily viewed. In addition to allowing the device to be rotated to allow easy viewing of the display, the belt clip should also be rugged and maintain the device in a position latched to the belt clip even when external forces are applied to the device housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a potable device in accordance with the present invention, 
     FIG. 2 is a perspective view of the back of the portable device in accordance with the present invention, 
     FIG. 3 is a rear elevational view of a belt clip in accordance with the present invention, 
     FIG. 4 is a front elevational view of a belt clip in accordance with the present invention, 
     FIG. 5 is a left side plan view of a belt clip in accordance with the present invention, 
     FIG. 6 is a right side plan view of a belt clip in accordance with the present invention, 
     FIG. 7 is a top plan view of a belt clip in accordance with the present invention, 
     FIGS. 8 and 9 are plan views of a bearing member in accordance with the present invention, 
     FIG. 10 is an perspective view of the bearing member of FIGS. 8 and 9. 
     FIG. 11 is a free body diagram illustrating the static loading of the belt clip in accordance with the present invention. 
     FIG. 12 is a cross-sectional view of the portable device in accordance with the present invention, and 
     FIG. 13 is an electrical block diagram of the portable device of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a plan view of a device  10  which can be worn on the belt in accordance with the present invention, The device  10  can be an electronic receiving device such as a paging receiver  1000  as will be described below, as well as other electronic devices which are well known and which are suitable to be carried on a belt or the waistband of a pair of pants or in a shirt pocket. When the device  10  is an electronic receiving device, the electronic receiving device is enclosed within a housing  12 . The electronic receiving device can have a viewing area  14  in which a display, such as an LCD display, or a number of visual alert indicators  16 ,  16 ′, and  16 ″, such as LED&#39;s, three of which are shown by way of example, are positioned. One or more controls, such as control  18  can be used to allow the device user to control the operation of the electronic receiving device. The device  10  can be secured to a belt by means of a belt clip  20 , as will be described in greater detail below. 
     FIG. 2 is a perspective view of the device  10  in accordance with the present invention, The device  10  is enclosed in a housing  12 . The belt clip  20  is shown in a rotated position which would occur when the belt worn device is worn on the belt to enable viewing an LCD display or visual alert indicators  16 ,  16 ′,  16 ″ which are located in a viewing area  14 . The housing  12  includes two bearing members  42  and  44  which are formed on the rear surface  50  of the housing  12  opposite the bottom surface  52  of the housing  12 , The first bearing member  42  is opposed to the second bearing member  44 , and the axis of the first bearing member  42  and second bearing member  44  is concentric with the axis of the pivot of the belt clip  20  which will be described below. The belt clip pivot is retained within circular cavities  46  and  48  which will be described further below. When the belt clip  20  is in the normal unrotated position, a boss  28  engages a cavity  40  which is located in the bottom surface  52  of the housing  12 . In the unrotated position of the preferred embodiment of the present invention, one of the clip elements, as will be described below, nests into a recess  54  in the back wall  50  of the housing  12 , thereby providing a lower profile to the belt clip  20  than would be achieved if the recess  54  were not present. Where the profile of the clip  20  and the housing  12  is not an issue, it will be appreciated that the recess  54  can be eliminated. 
     The housing  12  is preferably manufactured using a plastic material, such as a polycarbonate plastic which provides ruggedness to the housing  12  and to the bearing members  42  and  44 . The belt clip can be manufactured from any of a numbers of materials, such as plastic using an injection molding process, sheet metal using a metal stamping and forming process, or metals such as aluminum, magnesium or zinc can be used using a casting process. 
     FIG. 3 is a rear elevational view of a belt clip  20  in accordance with the present invention, Shown in this view is a rear clip element  22 , a boss  28  and a pivot  24 ,  26 . The pivot for the belt clip  20  is provided by two bosses a first boss, boss  24  and a second boss, boss  26 . The belt clip  20  also preferably incorporates a release mechanism  30  which is used to facilitate disengaging the boss  28  using a finger, as will be described in further detail below. 
     FIG. 4 is a front elevational view of a belt clip in accordance with the present invention, Shown in this view is a front clip element  32 , and the pivot  24 ,  26 . An opening  34  in the front clip element  32  can be provided to be used to attach an inexpensive lanyard to the belt worn device  10 . 
     FIG. 5 is a left side plan view of a belt clip  20  in accordance with the present invention, This view and FIG. 6 which is a right side plan view of a belt clip  20  in accordance with the present invention, show the features of the pivot  24 ,  26 . As shown, the belt clip  20  is formed from a U-shaped member  22 ,  32  which is intended to be hooked over a belt, although it can also be used to be hooked over the waistband of a pair of pants, the waistband of a skirt, or a shirt pocket as well. The U-shaped member includes a first clip element, the back clip element  22 , one end of which couples to the pivot and one end is free end and includes a boss  28 . The U-shaped member also includes a second clip element, the front clip element  32 , one end of which couples to the pivot and one end is free. 
     It is important to notice that the boss  24  which forms part of the pivot is different from the boss  26  which forms the other part of the pivot. The boss  26  has a profile which is circular, while the boss  24 , has a profile which is substantially D-shaped, i.e. circular with a flat cut parallel to the longitudinal axis of the pivot. The profile of the D-shaped boss  24  subtends an arc-length which is intentionally greater than 180°. The function of the belt clip to secure the device housing  12  and to allow the housing to freely rotate will be described in further detail below. 
     FIG. 7 is a top plan view of a belt clip  20  in accordance with the present invention, Shown in this view is the pivot  24 ,  26  and the boss  28 . 
     FIGS. 8 and 9 are plan views of a bearing member in accordance with the present invention, A first bearing member  46 , which is not shown includes a circular cavity which engages the boss  26  forming a portion of the pivot. The second bearing element  44 , shown in FIG. 8, includes a circular cavity  48  and also includes a slot  62  formed perpendicular to the axis of the circular cavity  48 . One surface of the slot  62  is tangent at point  80  to the circumference of the circular cavity  48 , and an axis  82  of the slot  62  is at a predetermined angle  72  relative to the back surface  50  of the housing  12 . The width  70  of the slot  62  is sufficient to accommodate boss  24 , when the D-shape of the boss is properly aligned to the slot  62 , as shown in FIG.  8 . The depth  78 , shown in FIG. 10, of the circular cavity  48  is sufficient to engage the length of the boss  24 , while the depth  76 , shown in FIG. 10, of the slot  62  is less than required to accommodate the length of the boss  24 , thereby creating an interference fit. 
     The belt clip  20  is assembled to the housing  12  by first inserting the boss  26  into the circular cavity  42  of the first bearing member  46 . The U-shaped member is then oriented such that the flat of the D-shape of the boss  24  aligns with the bottom of the slot  62 , as shown in FIG. 8, and then the U-shaped member is pivoted in a manner which forces the boss  24  through the slot  62  into bearing member  44  until the boss  24  drops into the circular cavity  48 . Once the U-shaped member engages both bearing members  42  and  44  as described, the bosses  24  and  26  of U-shaped member will not disengage the circular cavities  46  and  48  under any rotation of the housing  12  relative to the U-shaped member, except at the precise angle of insertion  72  of the boss into the slot  62 . FIG. 9 shows the relative orientation of the boss  24  to the slot  62  when the belt clip is latched to the housing. 
     FIG. 11 is a free body diagram illustrating the general case of the static loading of the belt clip. The X-axis lies horizontally on the page, while the Y-axis lies vertically on the page. A point load of magnitude P is applied at point A which would generate a counterclockwise rotation about the axis of rotation (O). Reaction forces are exerted at the axis of rotation (O), which corresponds to the pivot axis, and at the boss (C), which corresponds to the boss  28  when engaged with the cavity  40 . At static equilibrium, the forces along the X axis are defined by 
     
       
         ΣF X =P cos (θ)+R OX +R CX =0 
       
     
     where P cos (θ) is the force along the X-axis generated by the point load at point A, 
     R OX  is the component of the reaction force induced at point O along the X-axis, and 
     R CX  is the component of the reaction force induced at point C along the X-axis. 
     The forces along the Y axis are defined by 
     
       
         ΣF Y =P sin(θ)+R OY +R CY =0 
       
     
     where P sin (θ) is the force along the Y-axis generated by the point load at point A, 
     R OY  is the component of the reaction force induced at point O along the Y-axis, and 
     R CY  is the component of the reaction force induced at point C along the Y-axis. 
     Likewise, the moments about the axis of rotation (O) are defined by 
     
       
         ΣM O =P sin(θ)A X +P cos (Θ)A Y +R CY C X +R CX C Y =0 
       
     
     where A X  is the X component of vector OA, 
     A Y  is the X component of vector OA, 
     C X  is is the X component of vector OC, and 
     C Y  is is the Y component of vector OC. 
     It will be appreciated that deformation of the clip, and in particular the inner clip element  32 , is required to disengage the boss  28 . The deformation of the clip cannot be produced by applying a load at point A. As described above, this deformation can only occur when a force is applied to the release member  30 . 
     FIG. 12 is a cross-sectional view of the device  10  in accordance with the present invention, and is used to illustrate the principle behind the operation of the clip latching mechanism. When the device  10  is worn on the belt, a waistband, or hooked to a purse, a pocket, or any other item of apparel, any applied force  90  which is applied to the rear clip element  32  results in a rotation of the front clip element  22  relative to the rear clip element  32 . This rotation, or spreading of the U shaped member, results in a reaction force  96  being developed at the boss  28 . The higher the applied force  90  is, the higher the reaction force  96  generated would be. This results in the boss  28  being more securely seated in the cavity  40  and therefor less likely that the device housing  12  would be disengaged and rotated to the viewing position. 
     The device housing  12  can be released from the boss  28  in two different ways. One way is to apply forces  94  and  98  using as an example a finger and thumb to pinch the rear clip  22  and the release member  30  toward each other. This pinching motion results in a deformation of the front clip element  22  releasing the boss  28  from the cavity  40 , allowing the device housing  12  to then be freely rotated to view the display. A second way to release the boss  28  is to push on the release member  30 , which again would result in a deformation of the front clip element  22  releasing the boss  28  from the cavity  40 , allowing the device housing to then be freely rotated to view the display. 
     In summary, any force applied to the device housing which causes the back clip element  32  to separate from the front clip element  22  would more tightly engage the boss  28  with the cavity  40 , thereby preventing the device housing from being able to be rotated to the viewing position. Likewise, any force which is applied to the release member  30  which is sufficient to cause deformation of the front clip element  22  would release the boss  28  from the cavity  40 , thereby allowing the device housing  12  to be freely rotated to the viewing position. 
     FIG. 13 is an electrical block diagram of the belt worn device of FIG.  1 . Information transmitted is intercepted by antenna  1010  and is then processed by a receiver  1012  to recover the information. When the belt worn device  10  is a communication receiver, such as a pager, the recovered information can be either sequences of tones or digital information which identifies the pager and which also represents messages. The sequences of tones or digital information is processed by a decoder/controller  1014 , and when the received information matches information stored in a code plug  11026  an alert is generated. The alert can be audible, being delivered by an audible alerting device  1016 , such as a speaker or a transducer. The alert can also be tactile, being delivered by a tactile alerting device  1018 , such as a motor which spins an unbalanced mass. The alert can also be visual, being delivered by a visual alerting device  1022 , such as an incandescent lamp or an LED. The alert can be reset by way of switches  1020  which are also used to recover the message information which was received for viewing on a display  1024 , such as a liquid crystal (LCD) display which can be adapted to display numeric information or alphanumeric information. 
     While specific embodiments of this invention have been shown and described, further modifications and improvements will occur to those skilled in the art. All modifications which retain the basic underlying principles disclosed and claimed herein are with the scope and spirit of the present invention.