SMALL COIL DEVICE AND ASSEMBLING METHOD THEREFOR

PROBLEM TO BE SOLVED: To easily manufacture a small coil device of low voltage and heavy current output. SOLUTION: This small coil device is, on one surface, provided with a secondary winding 13 having a strip conductor 12, covered with an insulating sheet member 11 having the same width dimension as the part between a pair of flanges 2b and 2c of a bobbin 2, and terminal parts 12c and 12d extending in a width direction are formed at a start-end part 12a and a terminal-end part 12b of the strip conductor 12, respectively. A bellows-like expansion/ contraction part 12e is formed near the terminal part 12d of the terminal end part 12b of the strip conductor 12, while expansion/contraction is allowed, and guide grooves 14a and 14b with which each terminal part 12c, 12d of the start- end part 12a and the terminal-end part 12b of the strip conductor 12 is disposed are formed on a terminal leader part 2e of the bobbin 2. In addition, a step part 15, where each start-end parts 11a, 12a of the insulating sheet member 11 and strip conductor 12 is disposed, is formed on the surface of a cavity part 2a of the bobbin 2, and the secondary winding is wound near the surface of the cavity part 2a of the bobbin 2.