Biased eyeglass hinge

In a spring hinge for use in an eyeglass frame having a frame center part and two bows, each of which having an inner end comprising a metal portion,

• said spring hinge comprising,
• a sub-assembly including a receptacle having an open end and adapted to be secured to one of said bows at said inner end thereof,
• a first hinge member having an end portion extending into said receptacle,
• a plunger rigid with said first hinge member and extending into said receptacle,
• spring means urging said plunger into said receptacle, and
• a second hinge member pivoted to said first hinge member and secured to said frame center part,
• the improvement comprising,
• said receptacle comprising a flat box embedded in said bow and secured to said metal portion so that said open end of said receptacle is disposed near said inner end of said bow,
• said plunger comprising a U-shaped slider, which has a bight disposed in said receptacle and two legs axially guided in and extending out of said receptacle,
• a rod disposed in said receptacle and extending between the legs of said slider,
• a spring retainer disposed in said receptacle near the open end thereof, between the legs of said slider, and axially rigid with said rod, and axially fixed to said metal portion,
• said spring means comprising a coil spring, surrounding said rod, and disposed between the legs of said slider, and retained between said spring retainer and said bight, and urging said slider into said receptacle toward a position in which said rod is clear of said bight,
• said slider movable into said receptacle against the force of said coil spring until rod engages said bight,
• said first hinge member secured to said legs of said slider outside said receptacle, and comprising an overlapping portion which overlaps said receptacle on the outside thereof adjacent to said open end, and
• said first hinge member formed with a bevelled surface disposed outside said receptacle, between said overlapping portion and said slider, and facing said open end of said receptacle, whereby, when said hinge is retracted, said bevelled surface engages the outlet edge of said receptacle, at said open end thereof, so that there is no backlash during the movement of said bow from the inturned position to the normal open position.