Electro-acoustic micro-transducer having three-mode reproduction feature

• US 6,385,328 B1
• Filed: 05/24/2000
• Issued: 05/07/2002
• Est. Priority Date: 08/23/1999
• Status: Expired due to Fees

• Current Assignee: Microtech Systems Incorporated (Financière Cyclope SAS)
• Original Assignee: Microtech Systems Incorporated (Financière Cyclope SAS)
• Inventors: Yoo, Dong Ok, Kim, Kyung Ho
• Primary Examiner(s): TRAN, SINH N
• Application Number:
  US09/576,607
• Time in Patent Office: 713 Days
• Field of Search: 381/412, 381/419, 381/420, 381/409, 381/410, 381/411, 381/FOR.159
• US Class Current: 381/412
• CPC Class Codes: H04R 1/06 Arranging circuit leads; Relieving strain on circuit leads

Abstract

An electro-acoustic micro-transducer having a high power, high efficiency acoustic transducing feature and a three-mode broad band frequency reproduction feature on a micro-scale basis is provided. The electro-acoustic micro-transducer includes a yoke formed of an internal groove and a vertical incision portion for removing a vertical wall at one side surface, a permanent magnet installed in the groove of the yoke, a plate for forming a magnetic gap, a coil wound on the bobbin, a frame which surrounds the yoke, in which a throughhole is formed in the groove corresponding to the incision portion of the yoke, and a vibration diaphragm. Therefor, spaces in the incision portion of the yoke and the frame are formed so that a connection portion between the coil and lead wire can be prevented from contacting the yoke during vertical vibration, to thereby extend an up-and-down vibration width of the bobbin.

Claims

1. An electro-acoustic micro-transducer comprising:

a yoke formed of an internal groove and a vertical incision portion for removing a predetermined vertical wall at at least one side surface;

a permanent magnet installed in the groove of the yoke, for generating a non-alternating magnetic field;

a plate mounted on the upper surface of the permanent magnet, for forming a magnetic gap between the outer circumferential surface and the upper end of the yoke;

a coil wound on a bobbin, which generates an alternating magnetic field when an electric drive signal is externally applied via first and second lead wires and is disposed in the magnetic gap to be displaced up and down according to an interaction with a non-alternating magnetic field generated from the permanent magnet;

a cylindrical frame in which the outer circumferential portion surrounds the yoke at the state where the yoke is set to be positioned in the center, the outer circumferential portion is perpendicularly extensively formed in such a manner that a groove is formed therein and an externally communicating throughhole is formed in the groove corresponding to the incision portion of the yoke; and

a vibration diaphragm in which the bobbin is supported and the outer circumferential portion is supported in the upper end of the frame, for generating an acoustic sound in correspondence to the drive signal when the bobbin is displaced up and down,

wherein spaces in the incision portion of the yoke and the frame are formed of a magnitude of preventing a connection portion between the coil and lead wire from contacting the yoke during vertical vibration, to thereby extend an up-and-down vibration width of the bobbin.

2. The electro-acoustic micro-transducer according to claim 1, wherein the bobbin is rectangularly formed, where first and second band type electrode patterns are lengthily separated and formed on the upper end of the bobbin and a flexible PCB substrate where a coil winding bonding material coating area is located is cylindrically molded and formed on the lower end thereof, and wherein both ends of the coil are connected to one end of each electrode pattern, the first and second lead wires are connected to the other end of each electrode pattern, and the incision portion is a single incision formed in the yoke is formed opposing the connection portion between the lead wires and the electrode pattern.

3. The electro-acoustic micro-transducer according to claim 1, wherein the bobbin is rectangularly formed, where first and second band type electrode patterns are lengthily separated and formed on the upper end of the bobbin and a flexible PCB substrate where a coil winding bonding material coating area is located is cylindrically molded and formed on the lower end thereof, and both ends of the coil are connected to one end of each electrode pattern, the first and second lead wires are connected to an opposing position of each electrode pattern with respect to the center of the bobbin, and the incision portion is a pair of incision portions formed in the yoke are formed opposing the first and second connection portions between the lead wires and the electrode pattern.

4. The electro-acoustic micro-transducer according to claim 3, wherein the frame further comprises:

first and second guiders for molding the first and second lead wires withdrawn from the coil externally via each of the throughhole in zigzag form; and

an electrode terminal plate in which the first and second lead wires withdrawn via each guider are connected to the lower surface of the frame in either side of the throughhole and first and second electrode pads via which drive signals are applied externally are separately formed, wherein the first and second guiders are removed at the state where the other ends of the first and second lead wires are fixed to the first and second electrode pads.

5. The electro-acoustic micro-transducer according to claim 2, wherein the frame further comprises:

an electrode terminal plate in which the lead wire withdrawn from the coil is connected to the lower surface of the frame connected to the throughhole and first and second electrode pads via which drive signals are applied externally are separately formed.

6. The electro-acoustic micro-transducer according to claim 1, wherein the vibration diaphragm comprises:

a body extended from a neck portion on which the bobbin is attached to an outer end in cone shape;

a dust cap of a dome shape formed in the neck portion;

a rib continuously protruded at a predetermined width and height from the center of the dust cap to the outer end of the body; and

an edge for supporting the body to the frame, wherein the body, the dust cap, the rib and the edge are integrally formed.

7. The electro-acoustic micro-transducer according to claim 1, wherein the vibration diaphragm and further comprises a reinforcing body attached to the lower end of the vibration diaphragm, having a hole corresponding to the center portion of the dust cap, for reducing a non-linear distortion of the vibration diaphragm.

8. The electro-acoustic micro-transducer according to claim 3, wherein the flexible PCB substrate further comprises third and fourth band type electrode patterns electrically connected with the first and second band type electrode patterns in the inner side surface, for compensating for a linearity of DC magnetic field generated from the permanent magnet.

9. The electro-acoustic micro-transducer according to claim 1, further comprising:

a plurality of sound output holes and a cover plate combined in the lower end of the frame, for preventing foreign matter from entering the frame.

10. An electro-acoustic micro-transducer comprising:

a yoke formed of an internal circular groove and first and second vertical incision portions for removing a predetermined vertical wall at each side surface;

a permanent magnet installed in the groove of the yoke, for generating a non-alternating magnetic field;

a plate mounted on the upper surface of the permanent magnet, for forming a magnetic gap between the outer circumferential surface and the upper end of the yoke;

a coil wound on a bobbin, which generates an alternating magnetic field when a drive signal is applied and is disposed in the magnetic gap to be displaced up and down according to an interaction with a non-alternating magnetic field generated from the permanent magnet;

a cylindrical frame in which the outer circumferential portion surrounds the yoke at the state where the yoke is set to be positioned in the center, the outer circumferential portion is perpendicularly extensively formed in such a manner that a groove is formed therein and first and second externally communicating throughholes are formed in the first and second groove spaces opposing the incision portion of the yoke; and

a vibration diaphragm in which the bobbin is supported and the outer circumferential portion is supported in the upper end of the frame, for generating an acoustic sound in correspondence to the drive signal when the bobbin is displaced up and down,

wherein first and second groove spaces respectively formed by the first and second incision portions and the first and second groove spaces are formed of a magnitude of preventing first and second connection portions of the first and second flexible wires fixed to the bobbin from contacting the yoke and the frame during vertical vibration of the bobbin, in order to apply the drive signal externally, to thereby extend an up-and-down vibration width of the bobbin.