ULTRASONIC WAVE TRANSMITTER, ULTRASONIC WAVE RECEIVER, SHEET DETERMINATION DEVICE, AND IMAGE FORMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide protective members in at least either one of a transmitter or a receiver of ultrasonic waves to prevent a user from touching a vibration member.SOLUTION: Protective members 328 are arranged so that a distance L2 between an aperture plane of a receiving guide 325 and the center of the protective members 328 becomes half a distance L1 between the aperture plane of the receiving guide 325 and a surface of a reception vibration member 321. In other words, the protective members 328 are arranged at the center positions (L2=L1/2) between the aperture plane of the receiving guide 325 and the surface of the reception vibration member 321. With this arrangement, a transmission coefficient equal to a transmission coefficient when the protective members 328 are not present can be obtained despite the arrangement of the protective members 328.SELECTED DRAWING: Figure 3