| 摘要 |
PURPOSE:To control the temperature of a substrate for inter-digital electrode of a surface device and to control freely the delay time by using a material with which the transmission speed of an ultrasonic wave is varied by temperature to constitute said substrate. CONSTITUTION:The electric signal supplied to an inter-digital electrode 2 of the input side is converted into a surface wave which is transmitted on the main side of a substrate 1. This surface wave is converted again into the electric signal by an inter-digital electrode 3 of the output side. A power supply is connected between electrodes 6 and 7 provided to the side surfaces 8 and 9 of the substrate 1. Then a current is supplied to the substrate 1. The elastic constant, etc. of the substrate 1 have a big change at about the Curie point of a positive characteristic thermistor material of the substrate 1 in response to the electric conduction or non-conduction of the substrate 1. Then the elastic constant for transmission of the substrate 1 has a big change. The delay time can be freely controlled by the temperature of the substrate 1 owing to the change of the transmission speed of the surface wave. |
