| 摘要 |
355,919. Loud - speakers. N A A MLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, 13D, Emmasingel, Eindhoven, Holland. Aug. 5, 1930, No. 23424. Convention date, Sept. 27, 1929. [Class 40 (iv).] A magnet system for a loud-speaker comprising a ferro-magnetic armature has those vibrating parts, which, owing to their form and the properties of the material of which they are mademay give rise to resonance effects in the audible frequency range, because, due to their function, they cannot be made sufficiently rigid to have a natural frequency outside the audible range, made of a material having such internal damping that, in the neighbourhood of the fundamental frequency of the whole moving system, the resonance curve has a smooth course. The construction shown comprises a magnet 1 having pole shoes 2 .. 5, the poles 2, 5 being of one polarity and the poles 3, 4 of the opposite polarity. An armature 6, passing through a coil 7 and located in the polar gaps, has its ends secured to the centres of flat springs 11, the ends of which are clamped by screws. Two rods 8, a yoke 9 and a rod 10 connect the ends of the armature with a diaphragm. In such a construction, the springs 11 and preferably the yoke 9 are made of a pressed material prepared with the aid of artificial resins, such as pitch or that known under the registered Trade Mark " Bakelite." The rods 8, 10 can be made so stiff that they have natural frequencies outside the audible range and need not therefore be made of a material according to the invention. The Specification as open to inspection under Sect. 91 (3) (a) refers also to the application of the invention to microphones. This subject-matter does not appear in the Specification as accepted. |
