FIELD OF THE INVENTION  
         [0001]    The present invention relates to firearms, in general and, in particular, to a safety mechanism for preventing inadvertent firing of a firearm, particularly a handgun.  
         BACKGROUND OF THE INVENTION  
         [0002]    Firearms of various designs have long been known. One type of firearm has a mechanically activating primer. The energy needed to activate the primer is relatively low. Thus, these firearms suffer from a major disadvantage in that, if the firearm is dropped on the muzzle, the firing pin can move forward with sufficient energy to actuate the primer.  
           [0003]    There is shown in U.S. Pat. No. 4,208,947 a safety mechanism for a firearm including a hammer block engageable with the hammer to prevent the hammer from moving into engagement with the firing pin. The hammer block is manually shifted between its active and inactive positions through a safety cam having a positive driving connection with the block. As the cam is moved to shift the block from its non-blocking to its blocking position, the cam also engages the sear to release the sear from the trigger and to allow the hammer to move from its cocked position into a safety position in engagement with the hammer block. This safety mechanism is relatively complicated to manufacture and maintain.  
           [0004]    There is known, from U.S. Pat. No. 6,145,234 to Fluhr, a firing pin safety catch mechanism including a one-piece leaf spring extending the length of the breechblock of the firearm, the spring comprising a spring arm, a safety catch and a beveled release part. The safety catch has a first position, wherein the safety catch engages a catch surface of a firing pin, to secure the firing pin in a rest position, and a second position, wherein the safety catch disengages the catch surface, to release the firing pin for movement out of the rest position. The release part acts as a camming surface acting together with the hammer to release the spring.  
           [0005]    Another firing pin safety catch mechanism is shown in U.S. Pat. No. 4,658,529 to Bertolini. This mechanism includes an inertial firing pin with an annular groove. The safety is provided with a rib canted toward the hammer side of the firing pin. When the safety is moved to an “on” position, the rib enters the firing pin groove and cams the firing pin so as to retract and lock the pin in a sheathed position within the piston slide.  
           [0006]    Yet another firing pin safety device is shown in U.S. Pat. No. 4,090,316 to Volkmar. This patent discloses a firing pin which is pivotable between safety and firing positions, and a hammer which has a striking surface engaging the firing pin when the firing pin is in its firing position, and recess which receives the firing pin when in its safety position.  
           [0007]    All of these patents discloses safety devices wherein the firing pin lock is releases directly by the hammer, i.e., the lock and release are a single element.  
           [0008]    Accordingly, there is a long felt need for a safety mechanism for a firearm which will prevent inadvertent firing if the handgun receives a shock, by preventing the hammer from inadvertently activating the firing pin, and which is simple to manufacture and actuate, and which includes a safety mechanism to prevent inadvertent release of the firing pin lock.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides a safety mechanism for a handgun having a pivotal hammer arranged to activate a firing pin, the mechanism including a locking element for engaging the firing pin and preventing its movement, and a separate release element for releasing the locking element, the release element being releasable upon being hit by the hammer with a force above a pre-determined threshold.  
           [0010]    According to one embodiment of the invention, the locking element includes a firing pin plate through which one end of the firing pin passes, a blocking spring in the firing pin plate, a notch in the firing pin, the blocking spring engaging the notch in a locked orientation, and the blocking spring being out of engagement with the notch in a firing orientation, and a release element for causing the blocking spring to move from the locked orientation to the firing orientation.  
           [0011]    According to a preferred embodiment, the blocking spring is mounted in a groove cut in the firing pin plate, and held in the locked orientation by a plunger, the plunger being located so as to be hit by the hammer before the hammer hits the end of the firing pin.  
           [0012]    Preferably, the plunger has a conical cross section, the blocking spring being located so as to slide along the plunger when moving from the locked to the unlocked orientation.  
           [0013]    Most preferably, the hammer is arranged to hit both the plunger and the firing pin, the hitting of the plunger causing release of the blocking spring so that the firing pin is in the firing orientation.  
           [0014]    There is also provided, in accordance with the present invention, a method for preventing inadvertent firing of a firearm having a firing pin seated in a firing pin block and a hammer for actuating the firing pin, the method including mounting a locking element in the firing pin block, mounting a separate release element, coupled to the locking element, in the firing pin block, and releasably engaging the firing pin by the locking element, the locking element being released upon being hit by the hammer with a force above a pre-determined threshold. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which:  
         [0016]    [0016]FIG. 1 is schematic side view of a firing pin block as a safety mechanism for a firearm constructed and operative in accordance with one embodiment of the present invention;  
         [0017]    [0017]FIG. 2 is a perspective illustration of a firing pin plate in the safety mechanism of FIG. 1;  
         [0018]    [0018]FIG. 3 is a schematic plan view of a firing pin in the safety mechanism of FIG. 1;  
         [0019]    [0019]FIG. 4 is a schematic sectional illustration of a safety mechanism according to the present invention in a locking orientation;  
         [0020]    [0020]FIG. 5 is a schematic sectional illustration of the safety mechanism of FIG. 4 in a firing orientation; and  
         [0021]    [0021]FIG. 6 is a side view of a plunger in the safety mechanism of FIG. 4, showing schematically the locking and firing orientations.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    The present invention relates to a safety mechanism for handguns having a spring biased pivotal hammer for actuating its firing pin. The safety mechanism includes a mechanical locking element for retaining the firing pin, and a release element for releasing the locking element, the release element releasing the locking element upon engagement by the hammer with sufficient force to fire the handgun.  
         [0023]    By way of example, the safety mechanism of this invention is suitable for use with a Desert Eagle (registered Trademark) pistol. The mechanism is particularly well adapted to such a firearm, which is large enough to accommodate the safety device of the present invention. However, it should be understood that the invention is not limited to this particular firearm, but may instead be used with many other types of firearms.  
         [0024]    Referring now to FIG. 1, there is shown a schematic side view of a firing pin block  10 , constructed and operative in accordance with one embodiment of the present invention, which acts as a safety mechanism for a firearm. Firing pin block  10  acts together with the hammer  12  of the firearm which, as known, is arranged to hit one end of a firing pin  14 , so as to cause the firing pin, in turn, to activate a primer in the firearm. The end of firing pin  14  is held in a firing pin plate  16 , which holds it at the proper orientation for firing by the hammer.  
         [0025]    Firing pin block  10  includes a groove  20  in firing pin plate  16 , in which is seated a blocking spring  22 , held in place by a retaining pin  26 . Blocking spring  22  is arranged to releasably engage a groove in the firing pin  14 , as described below. A reciprocating plunger  24  is mounted in firing pin plate in contact with blocking spring  22 , and is designed to move the blocking spring from a locked orientation to an unlocked orientation. In the locked orientation, the groove of the firing pin is engaged by the blocking spring, so the firing pin cannot move forward to actuate the primer when the firearm falls. When the plunger is pushed by the released hammer, the blocking spring moves to a firing orientation, out of engagement with the firing pin, enabling the firing pin to move to activate the primer when hit by the hammer.  
         [0026]    A plunger spring  28  or other return element is provided in the firearm to return the blocking spring to the locking orientation after firing, as described below. The plunger spring can be any suitable spring which is disposed so as to be compressed by the plunger during firing and to return the plunger when released. One suitable arrangement is shown in FIG. 1, where plunger spring  28  is seated in a recess  29  formed between a slide and the plunger in firing pin plate  16 . In addition, the plunger spring does not permit the plunger to move (and release the firing pin) below a pre-defined threshold force, thereby preventing inadvertent release of the firing pin and inadvertent firing of the firearm.  
         [0027]    [0027]FIG. 2 is a perspective illustration of a firing pin plate  16  constructed and operative in accordance with one embodiment of the invention. In this embodiment, a planar groove  20 , with a recess  21  for the blocking spring, is created in the middle of the firing pin plate  16 , so that a looped blocking spring  22  (seen in detail in FIGS. 4 and 5) can be mounted therein. Firing pin plate  16  includes a throughgoing bore  23 , through which the end of the firing pin protrudes when the firearm is assembled. Blocking spring  22  is arranged to move into and out of bore  23  during operation of the safety mechanism. In order to permit locking of the firing pin  14 , a locking notch  30  is defined in the end thereof which extends through bore  23  in firing pin plate  16 , as shown in FIG. 3, a perspective illustration of a firing pin according to one embodiment of the invention.  
         [0028]    Operation of the safety mechanism of the present invention will now be described with reference to FIGS. 4, 5 and  6 . Referring to FIG. 4, there is shown a schematic sectional illustration of a safety mechanism  40  according to one embodiment of the invention in a locking orientation. As can be seen, a blocking spring  42  is mounted in a firing pin plate  44  and fixed at  46 , as by a retaining pin. Blocking spring  42  engages a plunger  50 , shown in detail in FIG. 6. As can be seen, plunger  50  is conical in shape. When blocking spring  42  is mounted in firing pin plate  44 , it contacts and can slide along the side of plunger  50 . Thus, in the locking orientation of FIG. 4, blocking spring  42  seats on the smaller diameter portion of plunger  50 , so that the blocking spring  42  partially blocks firing pin receiving bore  48  in the firing pin plate. When a firing pin is seated in bore  48 , spring  42  extends into the bore and engages the notch  30  on the end of the firing pin (seen in FIG. 3). Thus, even if the firearm is dropped on its muzzle, the firing pin is held in place in the firing pin plate by the blocking spring  42 . It will be appreciated that the default orientation is the locked orientation, with blocking spring  42  engaging notch  30  of the firing pin.  
         [0029]    When it is desired to fire the firearm, the hammer hits first the plunger  50  and then the firing pin. When plunger  50  is pushed into firing pin plate  44  against the action of the plunger spring, as seen in FIG. 5, the blocking spring slides along the conical plunger  50  as the diameter increases, which forces the spring out of bore  48  to a firing orientation  42 ′ (see also FIG. 6). As the blocking spring moves out of bore  48  to the firing orientation  42 ′, the locking notch in the firing pin is released by the locking spring. Now, when it is hit by the hammer, the firing pin is free to move to fire a cartridge. Thus, plunger  50  serves as a release element, which acts to release the blocking spring in order to permit firing of the firearm.  
         [0030]    While the invention has been described with regard to a particular embodiment, it will be appreciated that any locking element or mechanical mechanism, with any release element, which releasably engages the firing pin upon contact with the hammer above a predetermined threshold, can alternatively be utilized.  
         [0031]    It will be further appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims which follow.
A safety mechanism for a handgun having a pivotal hammer arranged to activate a firing pin, the mechanism including a locking element for engaging the firing pin and preventing its movement, and a separate release element for releasing the locking element, the release element being releasable upon being hit by the hammer with a force above a pre-determined threshold.