GB368303A - Improvements in and relating to apparatus for recording and reproducing sound - Google Patents

Abstract

368,303. Feeding webs. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Kellogg, E. W. ; 1185, Ardsley Road, Schenectady, New York, U.S.A.) Dec. 1, 1930, No. 36184. Convention date, Nov. 29, 1929. [Class 100 (i).] In a sound-recording or reproducing apparatus in which a sprocket 2 and a drum 3 engage with a film 1 in succession and are each driven at such a speed that an equal length of film is normally passed by both the sprocket and the drum, means are provided which are controlled by the number of sprocket holes passing in a given time period for adjusting the speed of the drum to maintain equality of average rate of feed by the sprocket and the drum. As shown, the film on its way from the sprocket 2 to the drum 3 passes over and drives a sprocket 20 connected to a gear wheel 22 similar to a gear wheel 23 connected to the sprocket 2. A pinion 24 meshes with the gear wheels 22, 23 and is carried by a bell-crank lever 25, 27 pivoted on a shaft 26 ; the arm 27 of this lever carries an electric contact 28 between two contacts 30, 31 in the circuit of a motor 40. This motor is geared to a screw-andnut device 37, 38, which adjusts the position of a friction pinion 13 on a cone. 12 in the driving mechanism of the drum 3. The motor 40 also drives a pinion 42 in mesh with a rack 34 on a rocking arm 33 carrying the contacts 30, 31. If the speeds of the sprockets 2, 20 are not the same, the pinion 24 is displaced one way or the other and the contact 28 touches the contact 30 or 31. This sets the motor 40 in motion, which corrects the speed of the drum by an adjustment of the friction pinion 13 ; at the same time the arm 33 is rocked to break off the motor circuit to prevent hunting or overcorrection. The sprocket device 20 may be replaced by an electrical contact-making counter. Specifications 293,381 and 295,378, [both in Class 40 (ii), Phonographs &c.], are referred to.