Trigger circuit controlled device for shutter speed adjustment in photographic cameras

Claim 1

A trigger circuit controlled device for the shutter speed adjustment in a photographic camera, including a trigger circuit for attaining a voltage and temperature independence of the shutter speed adustment combined with means forming a bridge circuit, means arranged in the branches of said bridge circuit for forming therein compensation voltages (Uk1,2) which are oppositely oriented to the bridge supply voltage (U 0), a capacitor (C) of variable charging capacity arranged in one branch of said bridge circuit, a source of voltage for charging said capacitor comprising the bridge supply voltage (U 0) reduced by one of said compensation voltages (Uk1), while another bridge branch has arranged therein resistance means furnishing a comparison voltage (U1), said resistance means being energized by a voltage (U0) also reduced by one of said compensation voltages (Uk2), whereby at the instant of balance of the bridge circuit and simultaneous release of the trigger the charging voltage of said capacitor is equal to said comparison voltage, and means producing said compensation voltages (Uk1,2) having the same temperature dependence as the circuit controlling the switch operations of the trigger.