Patent ID: 7508115

Claim:
A horn to which oscillations are applied by an oscillator, comprising: a portion in which a cross section perpendicular to a lengthwise direction of said horn has: a first region extending in a first direction perpendicular to the lengthwise direction; and a pair of second regions sandwiching the first region in a second direction perpendicular to the first direction and the lengthwise direction, wherein a sectional area of the first region has a maximum displacement in the first direction and a sectional area of the second region has a minimum displacement in the first direction at a first position of the horn, the first position corresponding to an anti-node of a standing wave of oscillations excited in the horn, and wherein a transition of the sectional area of the first region decreases in the first direction from the first position to a second position along the lengthwise direction, and a transition of the sectional area of the second region in the first direction increases from the first position to the second position along the lengthwise direction, the second position corresponding to a node of the standing wave.