GB442228A - Improvements in photophones - Google Patents

Abstract

442,228. Photophones. ZEISS, C., [Firm of], Carl-Zeiss-Strasse. Jena, Germany. Aug. 4, 1934, No. 22780. Convention date, Aug. 17, 1933. [Class 40 (v)] Relates to a photophone in which the pencil of light for the transmission of sound is modulated by a body that moves relatively to a totally reflecting surface and is rigidly connected to a part influenced by electromagnetic or electrostatic means. According. to the invention, the body and the electrically influenced part are mounted on the body containing the totally reflecting surface. As shown in Fig. 1, light from a source b passes through a condenser a to a rectangular prism c by which it is reflected through an objective d. A glass plate e lies against the surface c<1> of the prism and is mounted in an armature f, Figs. 2 and 3, which is pivoted at f<1>, f<2> on the surface c<1>. A tongue cut out from the armature is pressed against the surface cl by an adjusting screw h<1> carried by a bar h fixed to the legs of a horseshoe magnet l which holds the prism c and is supported by the housing m. An elastic arm i also presses against the armature near its axis of oscillation, the arm being pivoted on a bolt i<1> on the magnet l and actuated by a two-armed lever j pivoted at j<1> on the housing m so as to adjust the distance of the plate e from the surface c<1> or the pressure of the plate against this surface. The magnet l carries cores k located on the side of the armature facing the prism, speech currents passing through the windings surrounding these cores causing the armature f and plate e to oscillate thereby varying the pressure with which the plate e lies against the surface c<1> so as to control the amount of light which is reflected through the objective d. Flutes may be provided either on the surface c<1> or on the surface of the plate e co-operating therewith.