Abstract: A pole piece 31 is placed on a lower case 21. A pole piece 31 has a core 32 and a base 33. The bobbin portion 24 extends from the lower case 21 toward the internal space of a case 1 so as to surround the outer periphery of the core 32. The bobbin portion 24 is divided into a plurality of portions along the circumferential direction of the core 32. The bobbin portion 24 has basal parts 26 and elongated parts 27. The pole piece 31 is pressed from the above of the lower case 21 in a state where the bobbin portion 24 is passed through holes 35 of the base 33, to be positioned on the outer periphery of the core 32, so that the pole piece is fitted and placed into the lower case 21. A coil 41 is configured by winding a conductor wire 42 around the elongated parts 27 of the bobbin portion 24.

Abstract: A case 1 is formed of thermoplastic resin, and includes an upper case 11 and a lower case 21. The case 1 accommodates a pole piece 31, a coil 41, a magnet 51, a diaphragm 61, and so on. The pole piece 31 includes an core 32 and a base 33, and placed on the lower case 21. There are integrally formed on an upper face of the lower case 21, a wall 22 for defining a mounting position of the pole piece 31, a projection 23 for preventing a conductive wire 42 drawn our from the coil 41 from getting in touch with the base 33, and a bobbin part 24 for the conductive wire 42 to be wound therearound. A height of the projection 23 is set at an equal or larger value to or than a height of a surface of the base 33, and a contact of the conductive wire 42 with the base 33 can be avoided by the projection 23.

Abstract: A pole piece 31 is placed on a lower case 21. A pole piece 31 has a core 32 and a base 33. The bobbin portion 24 extends from the lower case 21 toward the internal space of a case 1 so as to surround the outer periphery of the core 32. The bobbin portion 24 is divided into a plurality of portions along the circumferential direction of the core 32. The bobbin portion 24 has basal parts 26 and elongated parts 27. The pole piece 31 is pressed from the above of the lower case 21 in a state where the bobbin portion 24 is passed through holes 35 of the base 33, to be positioned on the outer periphery of the core 32, so that the pole piece is fitted and placed into the lower case 21. A coil 41 is configured by winding a conductor wire 42 around the elongated parts 27 of the bobbin portion 24.

Abstract: A case 1 is formed of thermoplastic resin, and includes an upper case 11 and a lower case 21. The case 1 accommodates a pole piece 31, a coil 41, a magnet 51, a diaphragm 61, and so on. The pole piece 31 includes an core 32 and a base 33, and placed on the lower case 21. There are integrally formed on an upper face of the lower case 21, a wall 22 for defining a mounting position of the pole piece 31, a projection 23 for preventing a conductive wire 42 drawn our from the coil 41 from getting in touch with the base 33, and a bobbin part 24 for the conductive wire 42 to be wound therearound. A height of the projection 23 is set at an equal or larger value to or than a height of a surface of the base 33, and a contact of the conductive wire 42 with the base 33 can be avoided by the projection 23.