Patent GB-434134-A (GB)
Title: Improvements in or relating to telephone apparatus
IPC: H04M1/52
Filed: 1934-02-28
Abstract: 434,134. Intercommunication systems ; sets; loud - speakers. SHIPTON, E., 12, Dartmouth Street, Westminster. Feb. 28, 1934, No. 6481. [Class 40 (iv)] Relates to a loudspeaker cabinet for use in telephone systems, for example, as a master station in intercommunicating systems, in which a loud - speaking receiver is arranged behind keys, dialling or other switching means on a wall of the cabinet and the sound is emitted through openings adjacent one or more edges of the cabinet. One wall of the cabinet may be almost entirely occupied by keys ; the sound outlets may be narrow elongated slots adjacent to the edges of the wall carrying the keys &c. ; and the receiver may be of the moving-coil type with a large diaphragm. As shown in Fig. 2, the front of the cabinet is provided with keys 2 for making connections with the stations of an intercommunicating system and with callindicating lamps 3. A second row of lamps 3 may be provided below the keys to indicate the closing of other circuits by reverse movement of the keys. A hand-set (not shown), is supported on a switch on one side of the cabinet and this switch automatically disconnects the loud-speaker when the handset is in use. The moving-coil loud-speaker 9 is horizontal or inclined and directs the sound downwards on to the table 10. The sound exit is formed by the space 6 below the front wall of the cabinet, and there may also be tapered openings 8 at the bottom of the side walls. A microphone 11 is mounted within a hood 15 behind the orifice 6, the microphone may be in the front wall, the loud-speaker and the microphone may be mounted in an inclined baffle board, or the microphone of the hand-set may be situated within a sound-collecting hood and remain in circuit when the set is resting on the cradle switch. A flash-lamp bulb may be connected in series with the microphone to limit the current. The circuits may be arranged to permit use of the loud-speaker as microphone. In modifications, the loud-speaker is arranged on a vertical baffle, Fig. 3 (not shown), and the sound emitted through the aperture 6 or through an aperture at one or both sides of the front wall; or the loud-speaker is directed backwardly, Fig. 4 (not shown), towards sound passages leading to apertures at either side of the front wall of the cabinet. In another modification, shown in plan in Fig. 5, the loud-speaker 9 is directed forwardly and may be mounted in a baffle, and the sound may be directed to the side slots S by a wall 13 enclosing the keys. In modifications not illustrated, the loud-speaker is mounted in an opening in the back of the cabinet which forms a baffle, and one or more passages are arranged along the outside of the back and sides of the cabinet terminating in one or more openings at the top and bottom of the front wall or at its sides, or at the top, bottom and sides; a separate sound passage may be provided for the loud-speaker and the microphone ; or the cabinet is raised on legs to form sound apertures all around the base, or it may have legs along only one side and stand obliquely ; the loud-speaker may be mounted in the base of a desk-set provided with legs ; adjustable vanes may be provided in the sound apertures, or the position of the speaker in the cabinet, or in Fig. 2 its inclination, may be adjustable for controlling the volume of sound; the loud-speaker may be operated by a microphone or by an induction coil and a thermionic amplifier, from the earpiece of the handset. Specification 343,625 is referred to.