JPS5479620A - Diaphragm for speakers - Google Patents

Abstract

PURPOSE:To mutually sufficiently approach the outside circumferential parts of respective diaphragms and suppress excessive build-up in high resonance frequency by forming the diaphragms in such cone form that the inside circumferential part is circular and the four corners on the outside circumferential part assume an approximate rectangular shape. CONSTITUTION:The diaphragm is formed to such cone form that the inside circumferential part 1a thereof assumes a circle and the outside circumferential part 1b assumes an approximate rectangular shape wherein the four corners are hyperbolic. This diaphragm is made of, e.g., pulp or various foam molding materials, composite materials using paper or cloth, materials composed of a sandwich structure of a material of high rigidity such as metal plate or the like and a viscoelastic material, etc. Forming the outside circumferential part of this diaphragm not in circular form but in approximate rectangular form enables its sound pressure frequency characteristics to be made relatively flat because the theta in the formula-I (where Sh is the stiffness of the vertex part of the cone, 2theta is the vertical angle of the cone, tc is the thickness of cone paper, E is the Young's modulus of cone paper) is not constant in the circumferential direction and has a width of the maximum value theta and minimum value theta hence resonating only in the portions of a constant high frequency range does not occur.