| 摘要 |
PURPOSE:To improve weatherability and to maintain stability for a long period by sealing the end part of a microphone case with an urethane type elastic material with low gas permeability. CONSTITUTION:When a distance between a vehicle and a road is detected, ultrasonic wave transmitting and receiving are executed by a piezo-electric element 10, and the detecting action is executed through the lead wire 18 and a terminal pin 20 by a road surface distance detecting device. In such a case, after a urethane rubber-made spacer 24 is inserted, a terminal plate 22 is fitted into a vibration case 12, and in the space between the terminal plate 22 and the case 12, urethane-rubber adhesives is poured. For such a reason, the quantity of corrosive gas adsorbed into a microphone through a spacer 24 and an adhesives 26 is decreased widely. A vibration part 14 is a conical trapezoid, auxiliary resonance is suppressed, further, a metallic ring 16 is fitted into the case 12 and the side surface vibration is prevented. |
