Patent ID: 9457385
Filing Date: 2016-10-04
CPC Classification: B08B

Claim Text:
1. An ultrasonic cleaning method for cleaning an object in a liquid in which a gas is dissolved, the method comprising: irradiating the liquid in which the gas is dissolved with ultrasonic waves using an irradiation unit; measuring a first strength of acoustic waves of the liquid, at a fourth-order frequency of ultrasonic waves, and a second strength of the acoustic waves of the liquid, at a fundamental frequency of ultrasonic waves, as a second strength; calculating a ratio between the first strength and the second strength, by dividing the first strength by the second strength; adjusting the liquid by changing a dissolved gas concentration, optionally while stirring the liquid, so that the ratio determined in the calculating is larger than 0.8/1000; and cleaning the object while applying ultrasonic waves to the liquid so that the ratio is larger than 0.8/1000.