Abstract:
A vehicle mirror assembly has a mirror retention plate having two parallel free edges and a replaceable mirror plate having a first surface to which the mirror is attached and a second surface opposite said first surface. The second surface has two parallel edges which includes projections on one of said edges able to retain one of said edges of the retention plate. On the second edge of said second surface of the mirror plate is a releasable locking mechanisms engageable with the other of said free edges of the retention plate. This allows the mirror plate to be simply snapped into position and released by triggering the release mechanism.

Description:
PRIORITY 
     Priority is claimed as a national stage application, under 35 U.S.C. §371, to international application No. PCT/AU2012/001082, filed Sep. 11, 2012, which claims priority to Australian application 2011903694, filed Sep. 12, 2011. The disclosures of the aforementioned priority applications are incorporated herein by reference in their entirety. 
     This invention relates to improvements in external vehicle rear vision mirrors especially of the type used on trucks. In particular it relates to an easily replaceable mirror plate 
     BACKGROUND TO THE INVENTION 
     U.S. Pat. No. 5,615,054 discloses a vehicle mirror in which the mirror is attached to a mirror plate that is in turn attached by a sliding engagement with a mirror retaining plate in the mirror housing. This arrangement allows for replacement of the mirror plate if the mirror is broken or damaged. Complementary projections are provided on two parallel sides of the mirror plate and the retaining plate so that the mirror plate can be slid into a retention position. 
     Alternative for mirror plate constructions that also use a sliding engagement are disclosed in U.S. Pat. Nos. 6,325,519, 6,328,451, and 6,375,333. 
     These arrangements provide no means to lock the mirror plate to the retaining plate. It is an object of this invention to provide a more satisfactory means of securely fastening the mirror to the mirror assembly and also providing an easy release mechanism. 
     BRIEF DESCRIPTION OF THE INVENTION 
     To this end the present invention provides a vehicle mirror assembly having a mirror retention plate having two parallel free edges, a mirror plate having a first surface to which the mirror is attached and a second surface opposite said first surface having two parallel edges which includes projections on one of said edges able to retain one of said edges of the retention plate and which further includes on the second edge of said second surface of the mirror plate a releasable locking mechanism engagable with the other of said free edges of the retention plate. 
     This arrangement allows the mirror plate to engage the first edge of the retention plate and then be pushed to engage the second edge. The releasable locking mechanism preferably provides retention projections which can be moved into and out of engagement with the free edge of the retention plate. Preferably the releasable locking mechanism is actuated by actuation means accessible in the side or end wall of the mirror plate. 
     Preferably the releasable mechanism is rotary so that insertion of the mirror plate releases a latch that holds the edge of the retention plate. Rotation of the mechanism retracts the latch and allows the mirror to be removed from the retention plate. Preferably the releasable locking mechanism is actuated by rotating a shaft with a screw driver wherein the end of the shaft is accessible from the side or end wall of the mirror plate. 
    
    
     
       DETAILED DESCRIPTION OF THE INVENTION 
       A preferred embodiment will now be illustrated with reference to the drawings in which: 
         FIG. 1  illustrates an exploded view of the components of a first embodiment of the mirror plate of this invention; 
         FIG. 2  is illustrate the  4  stages of snapping the second edge of the mirror plate onto the retention plate of  FIG. 1 ; 
         FIG. 3  illustrates the mirror locking mechanism of the first embodiment before actuation; 
         FIG. 4  illustrates the mirror locking mechanism of the first embodiment after actuation; 
         FIG. 5  illustrates the unlocked configuration of a second embodiment of the mirror plate of this invention; 
         FIG. 6  illustrates the locked configuration of a second embodiment of the mirror plate of this invention; 
         FIG. 7  is an exploded view of the components of the locking mechanism shown in  FIGS. 5 and 6 ; 
         FIG. 8  illustrates details of the over tightening and anti rotation features of the embodiment of  FIG. 7 ; 
         FIG. 9  illustrates an alternative actuator for the mechanism shown in  FIGS. 5 to 8 ; 
         FIG. 10  illustrates a third embodiment of the invention; 
         FIG. 11  illustrates a fourth embodiment of the invention; 
         FIG. 12  illustrates a fifth embodiment of the invention; 
         FIGS. 13 to 16  illustrate a sixth embodiment of the invention; 
         FIGS. 17 to 23  illustrate a seventh embodiment of the invention; 
         FIGS. 24 to 29  illustrate an eighth embodiment of the invention. 
     
    
    
     The mirror assembly of  FIGS. 1 to 4  consists of a minor plate  10  having a rear surface  12  which incorporates the attachment mechanism. The ledges or hooks  15  on one parallel rib  14  are adapted to engage one free edge of the retention plate  60  of the minor motor  61 . This retention plate is usually of the kind described in U.S. Pat. No. 5,615,054 or U.S. Pat. Nos. 6,325,519, 6,328,451 and 6,375,333. 
     The latching mechanism  20  is spaced from rib  14  by a distance corresponding to the distance between the two edges of the mirror retention plate. 
     The latching mechanism  20  consists of a rotatable shaft  22  with its ends  23  held in the semicircular recesses  31 . 
     The shaft  22  incorporates a pair of levers  24  that are engaged by the edge  61  of the mirror retention plate  60 . Associated with each lever  24  is a headed spigot with a shaft  25  and a head  26 . The bar  40  seats over the shaft  22  and the end shoulders  42  seat in the recesses  34  of buttresses  33  so that the locking tabs  44  extending from the end shoulders  42  pass through a slot  35  in the face of the buttress  33  that lies adjacent the edge  51  of retention plate  50 . The locking tabs engage the edge  61  of the mirror retention plate. The bar  40  is biased by the springs  48  that are located in the recesses  34  of buttresses  33  and press against the shoulders  42 . The bar  40  also includes channels  45  that are sized to accommodate the shafts  25  of the spigots  26 . The shaft  22  is held in place by the springs  27  which bias the spigot heads  26  against the outside of the channels  45  as shown in parts  1 ,  2  and  3  of  FIG. 2 . When the retention plate is fully locked as in part  4  of  FIG. 2  the spigot heads  26  lie on top of bar  40  and the spigot shafts  25  are held in the channels  45 . 
     The release mechanism for the mirror plate consists of the sliding lever  51  and the rotatable lever  53 . The slidable lever  51  extends from the slot  36  in the external wall of the mirror plate  12  through the retention slot  37  and between the pillars  38  that also retain the shaft  22 . The rotatable lever  53  is attached to shaft  22  between the pillars  38 . When the mirror plate is clipped to the retention plate the rotatable lever  53  rotates to the vertical position as shown in  FIG. 4 . At this point the end of the slidable lever abuts the rotatable lever so that pushing the slidable lever  51  inwards rotates the rotatable lever  53  and pushes back the bar  40  against the springs  48 , so that the locking tabs  44  are withdrawn from engaging the edge  61  and allows the mirror plate  10  to disengage from the retention plate  60 . 
     In the second embodiment shown in  FIGS. 5 to 7  the mirror retention plate  60  and motor  61  are the same as in the first embodiment. The mirror support plate  70  is shown in  FIGS. 5 and 6  and on its rear face has a compartment to receive the mirror retention plate  60 . The ledges or hooks  75  on one parallel rib  74  are adapted to engage one free edge of the retention plate  60 . The latching mechanism  80  is located on rib  76  spaced from rib  74  by a distance corresponding to the distance between the two edges of the mirror retention plate. 
     The latching mechanism  80  consists of a hook  85  having a hollow central boss  87  which is internally screw threaded and ledges  88  which are tapered and adapted to lie on the edge of the mirror retention plate  60 . A worm  90  is attached at an approximate mid point of the rib  76  and is adapted to be rotatable within the boss  87  by rotation of the shaft  93 . Shaft  93  has a snap connection  94  that locks into the slot  91  of worm  90 . The other end  95  of shaft  93  fits into an opening in the edge of mirror plate  80  so that it can be easily accessed. The end  95  has a slot to enable it to be turned by a screw driver to move the tapered ledges  88  on to the edge of the mirror retention plate  60 . 
     The shaft  93  can be of variable length to suit different sizes of mirror plate  70 . The screw thread of the boss  87  is clipped to avoid over tightening of the shaft. As shown in  FIG. 8  B. The worm  85  also includes an anti rotation device in its connection to the rib  76  as shown in  FIG. 8C . 
     In  FIG. 9  a gear wheel  99  is used instead of a screw driver to rotate shaft  93 . The gear wheel can be accessed by a finger and engages the screw  97  on shaft  93 . 
     A third embodiment is illustrated in  FIG. 10  in which  10 A illustrates the locking mechanism in its attach or release position and  10 B in its locked position. Locking tabs  102  on the ends of shaft  101  are rotated out of contact with the edge of the mirror retention plate  60  by pressing the shaft  105  to compress the springs  107  to engage the rotation arm  103  which rotates the shaft  101 . 
     A fourth embodiment is illustrated in  FIG. 11  in which  11 A illustrates the locking mechanism in its attach or release position and  11 B in its locked position. Locking tabs  112  on the ends of pivoted shaft  111  are moved out of contact with the edge of the mirror retention plate  60  by pressing the shaft  115  to rotate the shaft  111  about the pivots  113  to compress the springs  117 . 
     A fifth embodiment is illustrated in  FIG. 12  in which  12 A illustrates the locking mechanism in its attach or release position and  12  B in its locked position. Locking tabs  122  on the ends of shaft  121  are rotated out of contact with the edge of the mirror retention plate  60  by turning the shaft  121  with a screw driver in slot  123  to compress the spring  127 . 
     In  FIGS. 13 to 16  a sixth embodiment is shown in which a worm driven pair of flexible arms are advanced to a lock position. The arms are retained using a wedge channel to resist removal. The flexible arms deflect to pass into the wedge channel.  FIGS. 17 to 23  illustrate the seventh embodiment in which the mirror plate is locked in place using a cam mechanism. The cam has a large surface to press to unlock the plate as shown in  FIG. 20  and a small arm to be pushed in to lock the plate as shown in  FIG. 19 . The cam is illustrated in  FIGS. 21 to 23  where the unlock tab  131  is limited in its deflection by rib  132 . The hooked tab  133  deflects to pass the mounting plate for locking. At the other side a lip  134  shown in  FIG. 22  provides downward pressure on the mirror plate in the locked position. 
       FIGS. 24 to 29  illustrate the eighth embodiment of the invention.  FIGS. 24   26  and  29  show the locked position and  FIGS. 25 and 27  show the unlocked position. The major components are shown in  FIG. 28 . The shaft  151  can be turned by a key or screwdriver in the end  152  from the side as shown in  FIG. 29 . The shaft  151  has arms  153  that click into slots  159  in the toggle wedge  158  rotation of the shaft  151  moves the toggle wedge against the mirror plate and locks the opposite edge under tabs  165  as shown in  FIG. 24 . The cams  154  have a flat face  154   a  shown in  FIG. 27  that prevents the lock from self closing. The cam face is an interference fit against pillar  157 . The smaller flat face  154  B shown in  FIG. 26  ensures that a positive lock position is achieved when the shaft  151  is rotated to the lock position. 
     Those skilled in the art will realise that this invention has solved a long standing problem of easily replacing and securely retaining a mirror rear. Those skilled in the art will also realise that this invention can be implemented in embodiments other than those described without departing from the core teachings of this invention.