Image Number 10 for United States Patent #4881212.
This invention is basically, an ultrasonic transducer that can be configured with good reproducibility, that includes an acoustic impedance matching member that gradually changes the acoustic impedance, and which is characterized byAn acoustic impedance matching member(2) configured with multiple unit layers (21, 22, 23, . . . 2n), each layer being thinner than a quarter-wavelength of an ultrasonic wave, andeach unit layer having a laiminated structure make up of heavy metal(52) and plastic(51) layers with a thickness ratio set between them to change gradually from the unit layer close to the ultrasonic oscillator to the unit layer close to the subject.