DIFF Subgroup
B06B 1/0644 Full Title
Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency > making use of electrical energy (B06B1/18, B06B1/20 take precedence) > operating with piezoelectric effect or with electrostriction (piezoelectric or electrostrictive devices per se H10N30/00)
Of 5 combined children, 0 exist in both systems.
5 codes are CPC-only extensions.