Patent Publication Number: US-2005137000-A1

Title: Rotatable latching device for a housing of a portable electronic device

Description:
FIELD OF THE INVENTION  
      This invention is concerned with latching devices and two part housings for portable electronic employing such latching devices wherein one housing member is movable between an open and closed position.  
      The invention is concerned particularly although not exclusively with two part housing latching devices and two part housings for a wireless communications device wherein one housing member is rotatable relative to the other housing member about a rotational axis perpendicular to a front surface of the device.  
     BACKGROUND ART OF THE INVENTION  
      Portable electronic devices these days offer a wide range of functionalities to suit the diverse needs of users of such devices. Whilst incorporating a greater range of functionalities into such devices, there has been a strong trend to miniaturisation to enable the devices to be more conveniently carried by a user, whether in a pocket or a purse, whether carried on a belt clip or even on a lanyard suspended from a user&#39;s neck.  
      There are, however, practical limitations to the extent to which many such portable electronic devices can be miniaturised without interfering with ease and convenience of use. For example, while a keypad readily may be miniaturised, it becomes difficult to operate with a user&#39;s fingers without errors due to simultaneous touching of closely adjacent keys. With miniaturised keypads, there is usually associated miniaturised indicia on or adjacent the keys which may make it difficult for some users to readily identify the particular functions of keys. Importantly however, miniaturisation of keypads in particular makes it much more difficult for a user to operate the device with a single hand. Where telephone handsets are concerned, there is a requirement to have a microphone and speaker spaced sufficiently to accommodate a user&#39;s mouth and ear, respectively.  
      In order to satisfy the conflicting requirements of compactness and ease and convenience of use, manufacturers have developed electronic devices with two part housings which are extensible in length by a telescopic sliding movement between the two housing members or a hinged joint between the housing members to enable the housing to be unfolded to an extended position or folded to a closed position.  
      A limitation of telescopically extendible two part housings is that to retain a robust coupling of the housing members, a substantial degree of overlap must be retained in the extended position, thereby substantially limiting the amount by which the housing may be extended.  
      Clam shall designs incorporating a main housing member and a flip type cover hinged along a top edge have proven popular as it is possible to increase the length of the device by a factor of two when the flip cover is in an open position. The flip cover also provides a convenient form of protection for a keypad located on the upper surface of the main housing member. In this configuration, the pivotal axis of the hinged coupling between the main housing member and the flip cover member is parallel to the front surface of the main housing member and extends transversely along an upper edge thereof. One such prior art device embodies a digital camera and also an LCD display located on an inner face of the flip cover member. When the flip cover member is pivoted to an open, extended position, the flip cover member is rotatable through 180° about a longitudinal axis of the flip cover member, the axis being substantially parallel to the face of the LCD display.  
      With most of the prior art flip type or clam shell two part housings, a spring biasing device is employed to retain the flip cover member in an open and/or closed state. One such device incorporates a cam member such that initially, the flip cover member is moved towards an open position against a biasing influence of the spring device and about half way through the travel of the flip cover member towards an open position, the cam member associated with the spring device goes through a neutral position into an over-centre position whereby the spring device urges the flip cover member towards the open position. While generally suitable for its intended purpose, such portable electronic devices require a two handed operation, at least to open the flip cover member.  
      Other known flip type or clam shell devices incorporate a unidirectional spring device which biases the flip cover member to an open position and a latch member to retain the flip cover member in a closed position against the biasing influence of the spring device. Flip type or clam shell portable electronic devices incorporating a latch are generally able to be opened with one hand.  
      A disadvantage with flip type or clam shell portable electronic devices having a spring biased flip cover member is that robust stop members are required to avoid damage to the flip cover member and its associated hinge as it reaches the limit of its open position. Moreover, even robust latch mechanisms are prone to wear or breakage which can render an otherwise fully functional portable electronic device as useless or too inconvenient for further use, particularly when the flip cover member is coupled to an on-off switch for the device.  
      In order to overcome or alleviate at least some of the problems associated with prior art portable electronic devices having extendible two part housings, recently it has been proposed to pivotally couple first and second housing members such that the housing members are able to undergo relative rotation about a pivotal axis extending substantially perpendicular to a front surface of the device. The cover member is manually rotated between the closed and open positions.  
     SUMMARY OF THE INVENTION  
      According to one aspect of the invention, there is provided a rotatable latching device for a portable electronic device having a two part housing wherein a first housing member rotates relative to a second housing member about an axis substantially perpendicular to a front surface of said device, said latching device including: 
          a body having a rotatable cam element, said cam element in use being urged to rotate about a rotational axis between a closed position and an open position by a torsional biasing member; and     a latchable detent follower selectively engageable with said cam element to retain cam element in said open or closed position against a restoring force applied by said torsional biasing member, said cam element being rotatable at least partially from an open position to disengage said detent follower to allow said cam element to selectively engage said detent follower at an intermediate position between, said open position and said closed position against the influence of said torsional biasing member.        

      Suitably, said cam element comprises a substantially circular member having at least one detent engaging surface adjacent a circumferential edge of said substantially circular member.  
      Preferably, said cam element comprises two or more circumferentially spaced detent engaging surfaces.  
      Said detent engaging surfaces may be formed on a radially outwardly extending protrusion on said cam element.  
      Said detent engaging surfaces may be radially inwardly extending recesses on said cam element.  
      Preferably, said detent engaging surfaces are at least partially complementary to an engaging surface of a detent follower of said detent follower.  
      The detent follower may be resiliently biased in a direction radially inwardly of said cam element.  
      Suitably, said detent follower may be selectively latchable in a retracted position by a releasable resiliently biased latching mechanism.  
      If required, the detent follower may be urged from an extended unlatched position to a retracted latched position by at least partial rotation of said cam element from said closed position to urge said radially outwardly extending protrusion into engagement with said detent follower whereby said cam element is urged to rotate to said open position under the influence of the restoring force of said torsional biasing member.  
      The latching mechanism may include a trip mechanism actuable as said cam element approaches said open position to release said detent follower to an unlatched position to engage with a further detent engaging surface to retain said cam element in said open position against the restoring influence of said torsional biasing member.  
      Suitably, said further detent engaging surface comprises a radially inwardly extending recess.  
      If required, said cam element may be retainable at at least one intermediate position between said closed position and said open position by a respective at least one radially inwardly extending recess on said cam element.  
      Suitably, said open position is located at from 150° to 210° from said closed position.  
      Preferably, said at least one intermediate position is located at from 70° to 110° from said closed position.  
      The body of said rotatable latching device may include an upright at least partially continuous wall surface to rotatably locate said rotatable cam element.  
      Suitably, said body includes at least one mounting member to secure said latching device in a housing member.  
      Preferably, at least a portion of said cam element is exposed via an aperture in said body to permit attachment of a housing member to said cam element for rotation therewith.  
      According to another aspect of the invention, there is provided a portable electronic device having a two part housing wherein a first housing member rotates relative to a second housing member about an axis substantially perpendicular to a front surface of said device, said latching device including: 
          a body having a rotatable cam element, said cam element in use being urged to rotate about a rotational axis completely between a closed position and an open position by a torsional biasing member; and     a latchable detent follower selectively engageable with said cam element to retain cam element in said open or closed position against a restoring force applied by said torsional biasing member, said cam element being rotatable at least partially from an open position to disengage said detent follower to allow said cam element to selectively engage said detent follower at a said open position and said closed position against the influence of said torsional biasing member, said body being securable to one of said first or second housing members and said cam element being securable to another of said first or second housing members.        

      Suitably, said cam element comprises a substantially circular member having at least one detent engaging surface adjacent a circumferential edge of said substantially circular member.  
      Preferably, said cam element comprises two or more circumferentially spaced detent engaging surfaces.  
      Said detent engaging surfaces may be formed on a radially outwardly extending protrusion on said cam element.  
      Said detent engaging surfaces may be formed on a radially inwardly extending recess on said cam element.  
      Suitably, said detent follower may be selectively latched in a retracted position by a releasable resiliently biased latching mechanism.  
      If required, the detent follower may be urged from an extended unlatched position to a retracted latched position by at least partial rotation of said cam element from said closed position to urge said radially outwardly extending protrusions into engagement with said detent follower whereby said cam element is urged to rotate to said open position under the influence  
      Suitably, said detent follower may be selectively latched in a retracted position by a releasable resiliently biased latching mechanism.  
      If required, the detent follower may be urged from an extended unlatched position to a retracted latched position by at least partial rotation of said cam element from said closed position to urge said radially outwardly extending protrusions into engagement with said detent follower whereby said cam element is urged to rotate to said open position under the influence of the restoring force of said torsional biasing member.  
      Preferably, said electronic device incorporates at least one display screen.  
      Suitably, said electronic device incorporates a display screen on an outer face of said first housing member, said first housing member being selectively rotatable relative to said second housing member to orient said display screen in a portrait or landscape configuration.  
      If required, said electronic device may include a digital camera device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In order that the invention may be more fully understood, and put into practical effect, reference will now be made to the preferred embodiments illustrated in the accompanying drawings, in which:  
       FIG. 1  shows an exploded view of a rotatable latching device according to one aspect of the invention;  
       FIG. 2  shows one side of the device of  FIG. 1  in an assembled state;  
       FIG. 3  shows an opposite side of the device of  FIG. 2   
      FIGS.  4  to  8  show schematically the operation of the latching device;  
       FIG. 9  shows a front view of a portable electronic device according to the invention when in a fully open position;  
       FIG. 10  shows a rear view of the portable electronic device of  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION  
      In the description of the preferred embodiments illustrated in the accompanying drawings, like reference numerals will be employed for like features where appropriate.  FIG. 1  shows a rotatable latching device  1  comprising a body  2 , a substantially circular rotatable cam element  3 , a torsional biasing member  4  in the form of a coil spring, a bearing plate  5  and a cover plate  6 . Body  2  comprises an annular retaining flange  2   a  and a substantially circular outer wall  7  with a radially extending detent follower cavity  8  projecting therefrom. Extending perpendicularly to and communicating with detent follower cavity  8  is a latch mechanism cavity  9 .  
      A detent follower  10 , locatable in cavity  8 , includes a nose member  11   a  having an engaging surface  11   b  formed on an edge of the nose member  11   a.  A hollow recess  12  extending rearwardly of detent follower  10  receivably locates a resilient biasing member  13  in the form of a compressible coil spring. A latching mechanism  14  also has a hollow recess  15  extending rearwardly thereof to receivably locate a resilient biasing member  16  in the form of a compressible coil spring. A trip mechanism  17  mounted on a front portion of latching mechanism  14  extends slidingly beneath detent follower  10  and in use extends outwardly from an aperture  18  formed in a side wall  19  of detent follower cavity  8 . A shouldered projection  20  is releasably engageable with a front wall  21  of detent follower  10 .  
      Rotatable cam element  3  comprises a substantially circular member  22  having a raised substantially circular boss  23  concentric therewith. Boss  23  includes adjacent cam like projections  24   a  and  24   b  with a nadir  24   c  therebetween. There are also spaced detent engaging surfaces in the form of tapering recesses  25 , 26  spaced circumferentially in an upright wall  27  (forming a circumferential edge) of boss  23 . A plurality of mounting apertures  28   a  are spaced circumferentially between wall  27  and a central locating flange  30  for mounting latching device  1  to a first housing member of a portable electronic device such as cellphone. Also, one end  29  of torsional biasing member  4  is locatable in an aperture  28   b  of cam element  3 . The opposite end  32  of torsional biasing member  4  protrudes locates in an aperture  31  in cover plate  6 . This therefore allows a torsional restoring force between rotatable cam element  3  and body  2  when assembled with cover plate  6  secured to body  2  by engagement between tapered abutments  33  formed about the periphery of body  2  and slotted recesses  34 ,  35  formed respectively in attachment flanges  36  and mounting flanges  37 , respectively.  
      Mounting flanges  37  include apertures  38  to permit attachment of the device  1  to a second housing member of a portable electronic device. Bearing plate  5  is configured and positioned such that when the latching device  1  is assembled, torsional biasing member  4  is constrained to be in an annular space defined by the top surface of bearing plate  5  and a lower surface of cover plate  6 .  
       FIG. 2  shows the latching device  1  of  FIG. 1  in an assembled state with cover plate uppermost.  
       FIG. 3  shows the assembled latching device of  FIG. 2  in an inverted state with a lower surface portion  40  of cam element  3  protruding through a central aperture surrounded by retaining flange  2   a.  Flanges  37  facilitate mounting of the latching device  1  in the second housing member of a portable electronic device. Apertures  28   a  in the exposed surface of cam element  3  permit attachment of device  1  in the first housing member to allow relative rotation of the respective housing members by rotation of cam element  3  within body  2 .  
      Referring generally to FIGS.  4  to  8  there is illustrated schematically the operation of the latching device  1  of FIGS.  1  to  3  located in a portable electronic device comprising the first housing member  42  and the second housing member  41 . For ease of explanation and understanding, cover plate  6 , biasing member  4  and bearing plate  5  are removed from FIGS.  4  to  8 . In this embodiment housing member  42  is a front housing member of the portable electronic device. As shown specifically in  FIG. 4 , the housing members  41 ,  42  are in a closed state and are maintained in that closed state against a preloaded restoring force of torsional biasing member  4  (shown in  FIG. 1 ).  
      The latching device  1  is mounted in housing member  41  and housing member  42  is secured on the exposed portion of cam element  3  thereunder. Rotation of housing member  42  relative to housing member  41  against the restoring force of preloaded torsional biasing member  4  (shown in  FIG. 1 ) is resisted by engagement between nose member  11  of detent follower  10  and cam like projection  24  on cam element  3 . As shown in  FIG. 4 , the latching device  1  is in the closed position or state. In the closed position the nose member  11   a  of detent follower  10  is located in the nadir  24   c  and thus the detent follower is in co-acting and engagement with projection  24   a  and nadir  24   c.  Also, the detent follower  10  is urged into engagement with cam element  3  under the influence of biasing member  13  and the shouldered projection  20  on latching mechanism  14  engages against front wall  21  of detent follower  10  under the influence of biasing member  16 . A stop member  45  (shown in phantom) is secured to housing member  42  between housing members  41  and  42 . Stop member  45  has a trip mechanism actuator  45   a  extending therefrom, the purpose of which will be described later.  
       FIG. 5  shows release of co-acting retention and engagement of the detent follower  10  and protrusion  24   a  by manual rotation of housing member  42  (shown in  FIG. 4 ) through about 5°-7° relative to housing member  41  in the direction shown by arrow  46 . In this position it will be noted that nose member  11   a  has moved out of nadir  24   c  up to the zenith of projection  24   a  and detent follower  10  is urged radially outwardly from cam element  3  against the restoring influence of biasing member  13 . Once the detent follower  10  has moved over the zenith of projection  24   a,  by manual rotation of housing member  42  through about 10°-15°, the detent follower  10  is disengaged from cam element  3 . In other words cam element  3  and detent follower  10  are latchingly disengaged from the closed position and housing member  42  is free to rotate in the direction of arrow  46  relative to housing member  41  towards an open position under the influence of the restoring force of torsional biasing member  4  (shown in  FIG.1 ). As will be apparent to a person skilled in the art, the open position is typically located between 150° to 210° from the closed position and it is usually located 180° from the closed position.  
       FIG. 6  shows housing member  42  orientated at about 90° relative to housing member  41  as housing member  42  rotates, about a rotational axis  50 , towards an open position. It will be noted that nose member  11   a  of detent follower  10  is retained in a retracted position by latching mechanism  14  as recessed aperture  54  in boss  23  passes nose member  11   a  of detent follower  10  and housing member  42  continues to rotate relative to housing member  41  unimpeded.  
       FIG. 7  shows cam element  3  latched in an extended or open position 180° from the initial latched closed position shown in  FIGS. 4 and 5 .  
      As housing member  42  rotates past the 90° position shown in  FIG. 6  it will be seen that stop member  45  (visible via an aperture  52  in housing member  41 ) and trip mechanism actuator  45   a  are positioned at substantially the same radial distance from the rotational axis  50  of cam element  3  as is trip mechanism  17 . When trip mechanism actuator  45   a  (visible via an aperture  51  in housing member  41 ) engages trip mechanism  17  it causes latching mechanism  14  to retract against the biasing influence of biasing member  16  to disengage shouldered projection  20  from the front wall  21  of detent follower  10 . Detent follower  10 , under the influence of biasing member  13  is urged radially inwardly until it engages in recess  26  in boss  23  as shown in  FIG. 7 . By virtue of the connection of housing member  42  to cam element  3 , the housing members  41 ,  42  of the device, typically a cellphone, adopt the configuration shown generally in  FIG. 9  whereupon the device may be used in its extended or open position.  
      After use, housing member  42  of the cellphone may then be rotated relative to housing member  41  in an opposite direction towards a closed position as shown by arrow  55  in  FIG. 8 . Initially as housing member  42  starts to move from its latched open position as shown in  FIG. 7 , manual pressure on housing member  42  causes follower  10  to be urged radially outwardly by a cam action between an inner wall surface of recess  26  and a corresponding edge of nose member  11   a.  The tip of nose member  11   a  moves radially outwardly until it engages wall  27  of boss  23 . Then as housing member  42  continues to be rotated in the direction of arrow  55 , shown in  FIG. 8 , against the restoring force of the torsional biasing member  4  (shown in  FIG. 1 ), the tip of nose member  11   a  engages the wall surface of boss  23  between recess  26  and recess  25 . As shown detent engaging surfaces or recesses  25 ,  25  are at least partially complementary in shape to the engaging surface of nose member  11   a  of the detent follower  10 . The nose member  11  then enters and engages recess  25  to latch housing member  42  in a 90° orientation if required. This is an intermediate position located 70° to 110° from the closed position and is usually 90° from the closed position. If it is not required to latch housing member  42  in the intermediate position of 90° orientation as shown in  FIG. 8 , housing member  42  may be moved to the latched closed position as shown in  FIG. 4  by manually rotating housing member  42  in the direction of arrow  55  shown in  FIG. 8 , firstly to disengage detent follower  10  from recess  25  and then to engage projection  24   a.  As the zenith of projection  24   a  engages the tip of nose member  11   a,  detent follower  10  is urged into the retracted position as shown in  FIG. 5 . In this position, the front wall  21  of detent follower  10  has been retracted sufficiently to enable latching mechanism  14  to move, to an extended position with shouldered projection lying in front of front wall  21 . Further rotation of housing member  42  causes projection  24   a  to move past detent follower  10  which latchingly engages cam element  3  in a closed position. The engagement of the detent follower  10  with nadir  24   c  ensures that the same closed position (without overrun) is achieved after each opening and closing of the device  1 . At the same time, shouldered projection  20  of latching mechanism  14  engages against front wall  21  of detent follower  10  to retain it in a retracted position as shown in  FIG. 4 .  
       FIG. 9  shows a front view of a portable electronic device in the form of a cellphone  60 , comprising the housing members  41 , 42 , according to the invention when in an extended position. The housing members  41 ,  42  are rotatable relative to each other about the axis  50  substantially perpendicular to a front surface  61  of housing member  41 . A keypad  62  comprises any suitable layout of keys to suit the functions of the cellphone  60  and a number of function switching keys  63  or additional function keys  64  also may be provided. A display  65  is mounted in housing member  42  and in the open position shown it is oriented in a portrait viewing mode. Housing member  42  includes a speaker aperture  66  and housing member  41  includes a microphone aperture  67 .  
       FIG. 10  shows a rear view of the cellphone  60  in a closed position. Located in the rear face  68  of housing member  41  is a lens assembly  69  of a digital camera device coupled to display  65  via a processor embodied in the cellphone.  
       FIG. 11  shows the cellphone of  FIGS. 9 and 10  with housing member  42  latched in an intermediate position between the open position as shown in  FIG. 9  and a closed position. In the intermediate position shown, display  65  is viewable in a landscape mode and is latched in that position as shown in  FIG. 8  as housing member  42  is rotated in the direction shown from an open position to a closed position.  
      When the cellphone is in the fully open position as shown in  FIG. 9  or in the partially closed intermediate position shown in  FIG. 11 , the digital camera function of the electronic device may be invoked by, say one of function keys  63 , 64  whereupon the display  65 , suitably a backlit LCD, may be actuated to display the view of lens assembly  69  in a portrait or landscape mode as desired. The digital camera may be actuated by one of the keys on keypad  61  or alternatively a key  71  located on the side of housing member  41 .  
      It readily will be apparent to a person skilled in the art that the rotatable latching device of the invention and portable electronic devices incorporating the latching device provide a convenient yet elegant solution to prior art portable electronic devices incorporating extendible two part housings. In particular, portable electronic devices incorporating the latching device according to the invention are simply and conveniently usable in a one handed operation wherein the front housing member may be gently urged out of its closed latched position by gentle thumb or finger pressure, depending upon in which hand the electronic device is being gripped, whereupon front housing member  42  rotates through 180° about rotational axis  50 . Closure of the device is equally easily achieved by a one or two handed operation with the added benefit of selective orientation of the display  65  either in a portrait or landscape mode.