| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to miniaturize and thin a toner sensor while maintaining high sensitivity by providing a coil wound around a coil bobbin in a head section, and surface-packaging the above coil on a wiring board, and making the wiring board concurrently serve as the cover of the toner sensor. SOLUTION: In a differential transformer 1, a plurality of projection-shaped flange-parts 3 is coaxially formed on the outer periphery of a coil bobbin 2, around which the primary and the secondary winding are wound. In addition, the input-output terminals 8a, 8b of the primary winding and the input-output terminals 9a, 9b, 10a, 10b of the secondary wiring are additionally provided in the lower part of a pedestal part 2b resin-formed into one body with the coil bobbin 2, and surface-packaged on a printed wiring board 7. The toner sensor becomes best suitable for its miniaturization and thinning by composing it surface-packagably. In addition, the wiring board 7 and the case 24 of the toner sensor are mutually firmly fastened with boss pins 13a, 13b. The wiring board 7 is commonly used as the case cover of the toner sensor to facilitate the reduction and thinning of the thickness of the toner sensor. |
