Speaker diaphragm assembly and a method of manufacturing the same

A method of manufacturing a speaker diaphragm, comprising the steps of:

• (a) placing a thin layer made of a resin on a lower mold for forming a sound radiating surface of said diaphragm;
• (b) placing an upper mold on said lower mold, said upper mold extending upwardly and having a hole at the top thereof for receiving a cap;
• (c) putting a raw material of a foam resin, of the same sort as said resin, in said upper mold in such a manner that said raw material is placed on said thin layer;
• (d) tightening said cap;
• and
• (e) heating said upper and lower molds to effect foaming of said raw material so that said thin layer is welded to the body of said diaphragm made of said foam resin.

A method of manufacturing a speaker diaphragm made of a foam resin, comprising the steps of:

• (a) putting a first raw material of a foam resin, the foam magnification of which is relatively small, in a mold constructed of a lower mold for forming a sound radiating surface of said speaker diaphragm, an upper mold extending upwardly from said lower mold, and a cap to be inserted in a hole made in said upper mold;
• (b) putting a second raw material of a foam resin, the foam magnification of which is relatively great, in said mold in such a manner that said second raw material is placed on said first raw material;
• (c) tightening said cap;
• and
• (d) heating said mold to effect foaming of said first and second raw materials so that said speaker diaphragm having said sound radiating surface, at which the density of the foam resin is greater than that at the inside of said speaker diaphragm, is obtained.

A speaker comprising:

• (a) a housing;
• (b) a magnetic circuit means having a magnetic gap, said circuit means being connected fixedly to said housing;
• (c) a voice coil bobbin reciprocally movable in said magnetic gap;
• (d) a voice coil wound around the bobbin;
• (e) an electric circuit having electrical connections between said voice coil and speaker terminals;
• (f) a damper connected between said voice coil bobbin and said housing;
• and
• (g) a diaphragm assembly having a body made of a foam resin, a sound radiating surface portion, and a supporting member, said body having a front end portion integrally formed with said sound radiating surface portion, a rear end portion, and a side surface extending between said sound radiating surface portion and said rear end portion, said rear end portion being fixedly connected to one end of said voice coil bobbin, said supporting member having one end connected to said voice coil bobbin and extending toward said sound radiating surface portion along said side surface to terminate at a point between said sound radiating surface portion and said rear end portion so that said supporting member covers half or less than half of the entire side surface, said supporting member being fixedly connected to said side surface to cover a portion of said side surface close to said rear end portion, said body having front and rear end portions, said foam resin constituting said body having uniform density throughout the inside of said body as formed by heating a first raw material having a relatively great foam magnification, said sound radiating surface portion having a density greater than that at the inside of said body as formed by heating a second raw material having a relatively small foam magnification, the sound radiating surface portion being made of the same sort resin as said foam resin of said body and integrally formed with said front end portion of said body.

A speaker comprising:

• (a) a housing;
• (b) a magnetic circuit means having a magnetic gap and connected fixedly to said housing;
• (c) a voice coil wound around a voice coil bobbin which is reciprocally movable in said magnetic gap;
• (d) electrical circuits for establishing electrical connections between said voice coil and speaker terminals;
• (e) a damper connected between said voice coil bobbin and said housing;
• and
• (f) a diahragm assembly having a body made of a foam resin, a sound radiating surface portion, and a supporting member, said body having a front end portion integrally formed with said sound radiating surface portion, a rear end portion, and a side surface extending between said sound radiating surface portion and said rear end portion, said rear end portion being fixedly connected to one end of said voice coil bobbin, said supporting member having one end connected to said voice coil bobbin and extending toward said sound radiating surface portion along said side surface to terminate at a point between said sound radiating surface portion and said rear end portion so that said supporting member covers half or less than half of the entire side surface, said supporting member being fixedly connected to said side surface to cover a portion of said side surface close to said rear end portion, said supporting member being made of a material having a low thermal conductivity, a recess on said side surface, said supporting member having through-holes for receiving respective electrical terminal means, the positions of said through-holes being selected so that said through-holes correspond to said recess.