Calendar watch

Claim 1

In a calendar watch including a clock mechanism, an improved date-indicator shifting mechanism effecting sharp, periodic advance of date-indicia of said watch, said mechanism comprising, in combination, a movable, rotatably supported calendar crown carrying dateindicating means in an annular array, a ring of radially inwardly directed teeth integrally formed with said movable crown and correlated with said dateindicating means, a platelike platen affixed to said watch and having a guide groove formed therein, a cam rotatably driven by the clock mechanism, projection means carried by said cam and rotatable therewith, said projection means engaging cooperating said teeth of said movable crown to urge said crown annularly in incremental steps at 24-hour intervals, a cam-carried shaft extending transversely of said cam, said shaft extending into and slidably disposed in said guide groove of said platen for reciprocal movement of said cam between a rest position and a displaced position, return spring means resiliently urging said cam and cam-carried shaft toward said rest position and opposing travel of said cam toward said displaced position, said cam being responsive to pressure of said projection means against one of said teeth of said movable crown to move along said groove in said platen to said displaced position and to bring said cam into positive engagement against mechanical stop means carried by said watch, means operating in conjunction with said cam for ensuring precise, stepwise incremental advancement of said calendar crown at said 24-hour intervals and comprising detent means operatively engaging said crown, said detent means comprising, in combination, a pivotally moUnted pawl including tongue means integral therewith, and spring means resiliently urging said pawl against said ring of said crown and urging said tongue means of said pawl into engagement with said ring teeth to seat said tongue means into interdental notches therebetween, said spring means opposing inadvertent, casual, gradual and uncontrolled annular shifting of said ring, yet responsive to positive opposing force transmitted thereagainst through said cam to permit sharp, angular displacement of said movable crown in finite fixed steps defined by spacing of adjacent said teeth of said ring and corresponding to arcuate separation between adjacent said date indicia carried by said calendar crown, said positive opposing force being developed upon and correlated with continued driven rotation of said cam after sliding abutment against said mechanical stop means carried by said watch, said opposing force developed being effective to overcome the force of the spring means bearing against said detent means, whereupon said cam undergoes said rotational movement and said projection means shifts said calendar crown arcuately to advance said crown one full incremental step.