GB262839A - Improvements in vibratory systems - Google Patents

Abstract

262,839. Western Electric Co., Ltd., (Bell Telephone Laboratories, Inc.). July 25, 1925. Phonographic recorders and reproducers.- Comprises means for rendering telephone instruments and phonographic recorders and reproducers uniform in their action over a wide range of frequencies. For this purpose the instrument is associated with a transmission line for absorbing mechanical vibrations, analogous to an electric line and comprising an elongated solid body of homogeneous vibration-dissipating material. In the embodiment shown a rubber tube or cylinder 36 is attached at one end to the input mechanism, such as a gramophone tool-arm 20, the other end being idle. The cylinder 36 may be of pure gum rubber, 9" long and ¢" in external diameter, or it may be of leather, felt, cork, or spongy lead. It may be of uniform section or tapered, and may be supported by a felt, cotton or spongy rubber ring at its idle end : or it may be supported throughout its length by a wrapping of cotton, felt, or the like resting upon a surrounding casing, or by an aluminium or like strip 35, Fig. 8, lying in a bore which is formed in the tube and filled if desired with loading material 36a such as lead shot. The magnitude of the cylinder 36 is so calculated that energy reflected from the idle end shall be dissipated before returning to the input end. The cylinder is shielded by a casing formed of angle irons 43, 45, which is universally pivoted to its mounting at the idle end. Attachment of filter to tool arm and armature. In the embodiment shown in Fig. 2 the tool arm 20, which carries an electromagnetic armature, it attached to the cylinder 36 by the drawing of its end 28, which is of rectangular section and tapered, into a corresponding hole in a disc 34, where it is held by the tension of the spring 38 which can be adjusted by the drawing in of the ball 40 by means of the string 42. In a modification, however, in which the cylinder 36 is stiffened by a strip of metal arranged in the inner bore of the cylinder, this strip takes the place of the spring 38; it is fixed to the tool-arm 20 at one end and to the end of the cylinder 36 at the other. Mounting of tool arm and armature. The tool arm is mounted on knife-edges so as to vibrate rotarily about the axis of the armature-carrying bar 28, Fig. 2, as described in Specification 258,530. Telephone transmitters and receivers. - Instead of being connected to a gramophone stylus as shown, the cylinder 36 may be connected through a multiplying lever to the diaphragm of a telephone transmitter or loud speaker.