Abstract:
A hinge assembly for use in connecting a cover to a frame of a personal digital assistant (PDA) or the like. The hinge assembly is arranged so that the cover will auto-close or auto-open depending on the angular orientation of the cover.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a hinge assembly for a cover and more particularly to a hinge assembly used to connect a cover to a frame of a personal digital assistant or the like.  
         BACKGROUND OF THE INVENTION  
         [0002]    Most personal digital assistants (PDA&#39;s) have protective plastic covers over their screens to prevent damage thereto. When such covers are used it is important that they can be securely held in either the opened or closed position. To this end, some cover arrangements for PDA&#39;s have included catches or stoppers which maintain the cover in the required open or closed position. However, it has been found that over time and with continued use these catches tend to wear thereby preventing the cover from being maintained in the open position. This is a very annoying for the user because the dropping cover will then tend to obscure the user&#39;s visibility of the PDA&#39;s screen.  
           [0003]    U.S. Pat. No. 5,996,178 describes a hinge suitable for use in a foldable electronic device. The hinge system described in U.S. Pat. No. 5,996,178 relies on axial force from the compression spring to cause rotation of the cover. The hinge system is quite complicated and involves a considerable number of parts. The configuration of the hinge system is also such that additional axial space is required to locate the hinge system.  
           [0004]    The present invention seeks to provide an improved hinge assembly for the cover of a PDA or the like which securely maintains the cover in the desired open or closed position, that has a reduced number of component parts and which is compact in design.  
         SUMMARY OF THE INVENTION  
         [0005]    According to a first aspect of the present invention there is provided a hinge assembly for connecting a cover to a device, said assembly including a boss member on which a biasing means is arranged to be mounted, a cover connection member arranged to be mounted on said device, said connection member having a first end portion including cam means arranged to interact with at least one portion of said biasing means and a second portion to which said cover is arranged to be connected.  
           [0006]    Preferably, said biasing means is a torsion spring.  
           [0007]    Preferably, the device has a side wall and the cover connection member is arranged to extend through an aperture in the side wall.  
           [0008]    Preferably, the torsion spring includes a circular portion and a pair of elongate portions which extend substantially parallel to one another. As an alternative to the torsion spring including a circular portion, it may include an oval shaped portion.  
           [0009]    The boss member preferably includes a body portion and an enlarged end portion. The torsion spring is arranged to be mounted on the boss member so that the circular portion of the torsion spring is located on the body portion of the boss member. The enlarged portion of the boss member serving to prevent the torsion spring from disengaging from the boss member.  
           [0010]    Preferably, the cam means of the connection member means includes first and second pairs of opposed parallel surfaces. The first and second pairs of opposed surfaces extending perpendicularly to each other and preferably with each adjacent first and second surface being joined by a curved joining surface.  
           [0011]    The first portion of the connection member also includes means to engage against the torsion spring to thereby prevent the connection member from inadvertently disengaging from the aperture formed in the side wall. The engagement means preferably includes an enlarged portion adjoining the cam means and arranged to contact against at least one of the elongate portions of the torsion spring so as to thereby prevent the connection member from returning through the aperture formed in the side wall.  
           [0012]    The second portion of the connection member preferably includes first and second cylindrical portions. The aperture located within the side wall of the device is preferably configured to receive said first and second cylindrical portions of the connection means so that the connection means can rotate there within.  
           [0013]    The configuration of the first and second cylindrical portions and the aperture being arranged to prevent the connection member from passing all the way through the aperture.  
           [0014]    The first cylindrical portion is preferably located adjacent the cam means and has a reduced diameter as compared with the diameter of the second cylindrical portion.  
           [0015]    The cover and an end part of the second cylindrical portion of the connection member preferably include complimentary shaped connectors to enable the cover to be connected to the connection member. The complimentary shaped connectors preferably include male and female connectors. The male connector is preferably located on the cover and may adopt a “cross” or “minus” cross-sectional configuration. The male or female connector on the cover is preferably formed on a hinge member which extends from the cover. The cover preferably includes a pair of hinge members, each hinge member having a connector mounted or formed thereon which is arranged to be received in a respective complimentary connection member formed in respective side walls of the device.  
           [0016]    The boss member and the connection member are preferably made from a plastics materials. The cover is also preferably made from a plastics material.  
           [0017]    According to a second aspect of the invention there is provided an assembly including a device having opposed side walls, a cover arranged for connection to the device and at least one hinge assembly, said at least one hinge assembly including a boss member on which a torsion spring is arranged to be mounted, a cover connection member arranged to be mounted on one of said side walls, said connection member having a first portion including cam means arranged to interact with at least one portion of said torsion spring and a second portion to which said cover is arranged to be connected.  
           [0018]    Preferably, the assembly includes a pair of hinge assemblies.  
           [0019]    According to a third aspect of the invention there is provided a hinge assembly for connecting a cover to a device, the cover being arranged to move between a fully open and a fully closed position, the hinge assembly including a cover connection member arranged to join said cover to said device and biasing means arranged to engage with a portion of said connection member and to bias said cover towards either said fully opened or said fully closed position depending on the orientation of the connection member. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0021]    [0021]FIG. 1 is a perspective view of a PDA frame and a cover prior to attachment thereto.  
         [0022]    [0022]FIG. 2 is a perspective view of a cover attached to a PDA and with the cover in the closed position.  
         [0023]    [0023]FIG. 3 is an enlarged view of the circled portion shown in FIG. 2.  
         [0024]    [0024]FIG. 4 is a perspective view of the cover shown in FIG. 1.  
         [0025]    [0025]FIG. 5 is an enlarged view of the circled portion shown in FIG. 4.  
         [0026]    [0026]FIG. 6 is an assembly view showing the connection member, torsion spring and a portion of a PDA frame.  
         [0027]    [0027]FIG. 7 is an end view of the connection member showing the female connection into which the male connection of the cover is arranged to be attached.  
         [0028]    [0028]FIG. 8 details the angular position of the cam when the cover is in a closed position.  
         [0029]    [0029]FIG. 9 provides references for detailing a preferred ratio of the first and second cam surfaces of the cam.  
         [0030]    [0030]FIGS. 10 and 11 provide partial side views of the frame showing a cover connected thereto and a stopper.  
         [0031]    [0031]FIG. 12 details the angular position of the cam when the cover is in the fully opened position.  
         [0032]    [0032]FIG. 13 details a “plug and play” embodiment of the hinge assembly.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    [0033]FIG. 1 illustrates a frame  10  arranged to receive a PDA (and other electrical components) and a pivotal cover  12 . The frame  10  includes first and second pairs of opposed side walls  14 ,  16  arranged so as to enable a PDA to be located there within. The PDA is arranged to be secured to the frame  10  by four threaded connectors (not shown) which are arranged to pass through anchor points  18  and into the underside of the PDA. The cover  12  is arranged to be hingedly connected to the frame  10  by a pair of hinge assemblies  20 . The configuration of the hinge assemblies  20  is best illustrated in FIGS. 3 and 6.  
         [0034]    Each hinge assembly  20  includes a boss member  22  having a main body  22   a  and an enlarged head  22   b . The boss member  22  is integrally formed or attached to a mounting plate  24 . Mounting plate  24  is arranged to be located on an inner side  26  of one of the first side walls  14 . The mounting plate  24  has a circular aperture  28  formed therein which is positioned for coaxial alignment with an aperture  29  which extends through the side wall  14 .  
         [0035]    The hinge assembly  20  also includes a torsion spring  30  which is arranged to be mounted on the boss member  22  and a cover connection member  32 . The cover connection member  32  includes a first portion  34  which incorporates a cam  36  and an engagement member  38 . The cam  36  is formed by first and second pairs of opposed cam surfaces  40 ,  42 . Extending between each adjacent first and second cam surface  40 ,  42  is a curved joining surface  44 . The function of the cam  36 , the first pair of opposed cam surfaces  40 , the second pair of opposed cam surfaces  42  and joining surfaces  44  will be described in more detail below.  
         [0036]    The second end portion of the cover connection member  32  includes first and second cylindrical portions  46 ,  48 . The first cylindrical portion  46  is located adjacent the cam  36  and is of reduced diameter when compared with the diameter of the second cylindrical portion  48 . The diameters of the first and second cylindrical portions  46 ,  48  are such that they respectively fit within the apertures  28 , 29  to prevent the connection member  32  from passing entirely inwardly through the apertures  28 ,  29 , whilst still allowing the connection member  32  to freely rotate therewithin.  
         [0037]    The torsion spring  30  includes a circular portion  30   a  and a pair of elongate portions  30   b  which extend substantially parallel to one another. The circular portion  30   a  of the torsion spring  30  is sized so that it can be passed over the boss member  22  and located on the main body  22   a  of the boss member  22 . The enlarged head  22   b  of the boss member  22  is sized so as to prevent the torsion spring  30  from inadvertently being removed from the boss member  22 .  
         [0038]    To assemble the hinge assembly  20  to the first side wall  14 , the connection member  32  must first be located within the coaxially aligned apertures  28 ,  29  formed respectively within the mounting plate  24  and the side wall  14 . When the connection member  32  is correctly located within these apertures  28 ,  29  the cam  36  and engagement member  38  protrude beyond the vertical plane of the mounting plate  24 . The elongate portions  30   b  of the torsion spring  30 , are then arranged so that they extend against the opposed surfaces  42  of the cam  36 . Thereafter, the circular portion  30   a  of the torsion spring  30  is pushed over the enlarged head  22   b  of the boss member  22  so that the circular portion  30   a  of the torsion spring  30  is located around the main body  22   a  of the boss member  22 . FIG. 3 shows clearly each of the elongate portions  30   b  of the torsion spring  30  positioned against a respective one of the first cam surfaces  40 .  
         [0039]    As best illustrated in FIGS. 4 and 5, the cover  12  includes depending hinge members  50  which each have a connector  52  attached or formed thereto. As illustrated in FIG. 5, the connector  52  of this embodiment is a “minus shaped” male connector  52 . The male connector  52  is arranged to be received within a complementary shaped female connector  54  formed in the end face  48   a  of the second cylindrical portion  48  of the connection member  32 . The complementary shaped female connector  54  is best shown in FIG. 8.  
         [0040]    As illustrated in FIG. 1, a hinge assembly  20  is arranged to be connected to the upper portion of each of the first side walls  14 . The cover  12  with hinge members  50  is then connected to the frame  10  by outwardly flexing each of the hinge members  50  so that the male shaped connectors  52  pass over their respective side walls  14 . The male shaped connectors  52  are then located within their respective female connectors  54  formed in the end face  48   a  of their respective connection members  32 . FIG. 3 illustrates the connection of one hinge member  50  to its respective hinge assembly  20 . The cover  12  as illustrated in FIG. 3 is in the closed position.  
         [0041]    When the cover  12  is in the closed position, the elongate portions  30   b  of the torsion spring  30  contact against respective first surfaces  40  of the cam  36  and the cam  36  extends at an angle of approximately  30  degrees to the horizontal. This is best illustrated in FIG. 8.  
         [0042]    When the user rotates the cover  12  to move it into an open or in-use position, the engagement between the male connector  52  and the connection member  32  causes the connection member  32  to rotate within the apertures  28 ,  29 . As this occurs, the first pair of cam surfaces  40  of the cam  36  are also caused to rotate. However, this rotational movement of the connection member  32  is resisted by the contact between the elongate portions  30   b  of the torsion spring  30  and the first pair of cam surfaces  40 . Accordingly, this resistance by the torsion spring  30  tends to return the cover  12  to the closed position. This provides an “auto-close” feature for the cover  12 . Continued rotation of the cover  12  towards the in-use position overcomes this resistance so that the elongate portions  30   b  of the torsion spring begin to come into contact with the curved joining surfaces  44  of the cam  36 . As this occurs the cam  36  is said to reach a neutral or toggle position. If the cover  12  is then rotated further towards the in-use position, the connection member  32  will also rotate until the elongate portions  30   b  of the torsion spring  30  come into contact with the second pair of cam surfaces  42  of the cam  36 . When the elongate portions  30   b  of the torsion spring  30  contact the second pair of cam surfaces  42  of the cam  36  the cover  12  is snapped to the open or in-use position. This results in the cover  12  having an “auto open” feature.  
         [0043]    As best illustrated in FIG. 10, a stopper  60  is provided on the outer side of the side wall  14  of the frame  10 . The stopper  60  is arranged to engage with a portion  12   d  of the cover  12  so as to prevent the cover  12  from moving once the cover  12  has reached an inclination of  1200  from the horizontal. As the stopper  60  prevents any additional pivotal movement of the cover  12 , the resistive force of the torsion spring  30  will try to open the cover  12  further, thereby resulting in the cover  12  being held firmly in the open or in-use position.  
         [0044]    It will be appreciated from the above description that the configuration of the cam  36  and its relationship with the elongate portions  30   b  of the torsion spring  30  is such that the torsion spring  30  tends to hold the cam  36  and the connected cover  12  in the closed position until the cover  12  is rotated past the neutral or toggle position. If rotation of the cover  12  is stopped before the cam  36  reaches the neutral or toggle position, the cover  12  will snap to the closed position. However, once the cover  12  is rotated past this neutral or toggle position, the elongate portions  30   b  of the torsion spring  30  will contact the second cam surfaces  42  and thus the cover  12  will be raised to the fully opened position. The cover  12  will be held in the fully opened or in-use position under the action of the torsion spring  30 .  
         [0045]    In a particularly preferred embodiment of the invention, the cover  12  can be fully opened to an angle of approximately 120 degrees to the horizontal. The neutral or toggle position of the cam  36  occurs when the first pair of opposed surfaces  40  are at an angle of 90 degrees to the horizontal. This is best illustrated in FIG. 12.  
         [0046]    In order to obtain the required tactile feel when opening the cover  12 , or in other words to achieve the desired opening smoothness, the cam ratio as best illustrated in FIG. 9 should preferably be L/B=3.4/1.3=2.6.  
         [0047]    The hinge assembly  20  described above is considered to be advantageous because it is simple in construction and uses a minimum number of component parts. Furthermore, the inclusion of this type of hinge assembly does not increase the axial dimension of the PDA frame. This is extremely important so that the size of the combined PDA and cover can be maintained as small as possible.  
         [0048]    The hinge assembly  20  of an embodiment of the present invention provides a reliable method by which the cover  12  can be maintained in either the closed or open position and no additional locks or catches are required in order to ensure that the cover is maintained in the required position. Furthermore, the hinge assembly  20  is made of lightweight plastics material and therefore does not greatly increase the overall weight of the device.  
         [0049]    It will be appreciated by those skilled in the art that although the male connector  52  on the cover  12  is described as having a “minus shaped” configuration other configurations are envisaged. For example, the connector  52  may adopt a “cross shaped” or “star shaped” configuration. It is also envisaged that the connector  52  on the hinge member  50  may be a female connector which is arranged to receive a male connector  54  formed on the connector member  32 . The only limitation to the configuration of the connector  52  is that is must properly engage with the complementary shaped connector of the connection member  32  so that rotational movement of the cover  12  results in rotational movement of the connector member  32 .  
         [0050]    It will also be appreciated by those skilled in the art that the hinge member  50  must be sufficiently flexible to enable it to be flexed outwardly so that the connector  52  can pass over the side wall  14  and then be located within the complementary shaped connector  54  formed in the connection member  32 .  
         [0051]    It is envisaged that the hinge assembly previously described could be modified for “plug and play” installations. As shown in FIG. 13 such a “plug and play” assembly  100  would include a mounting plate  24 ′, a boss member  22 ′, a torsion spring  30 ′ and a cover connection member  32 ′. These components would be pre assembled so that they could simply be plugged or slotted onto a frame  10 ′. The frame  10 ′ would include an appropriately positioned groove  105  or aperture which is shaped to receive and engage with the mounting plate  24 ′.  
         [0052]    While the embodiments described herein are preferred, it will be appreciated from the specification that various alternatives, modifications, variations or improvements therein which may be made by those skilled in the art are within the scope of the invention, which is defined by the claims.