| 摘要 |
PURPOSE:To eliminate ineffective oscillation and control radiation noise to minimum by a method wherein the main power source of an oscillation circuit which oscillates a piezoelectric element for emitting ultrasonic oscillation is opened and closed by the switching part of a liquid level detector, which coexists with the circuit on the same printed wiring board. CONSTITUTION:When the liquid level in a liquid pan 14 is normal, that is, a float including a magnet 10 is located at a position A, the lead switch 8a of a liquid level detector 8 is turned on and power rectified by a diode bridge 9 which coexists with the switch 8a on the same printed wiring board 12 is supplied to a Colpitts type self-osciliating circuit 13. The current becomes the base bias of a transistor 3 with the divided potential caused by resistor 5, 6 and a piezoelectric oscillating element 4 is stably oscillated and the atomization of liquid is promoted by the ultrasonic oscillation. When the liquid level of the liquid to be atomized lowers and the float 11 reaches a position B, the switch part 8 opens to stop the operation of the circuit 13. Thus, ineffective oscillation is eliminated and the deterioration of the element is prevented and because of the coexistance of the switch and the circuit, radiation noise can be controlled.
|
