| 摘要 |
PURPOSE:To prevent electric discharge of the element and caused by a pyroelectric effect, by coating the surface and the side of an elastic surface wave element which is used for the filter of VHF and UHF bands, etc., with an insulator. CONSTITUTION:The surface (the surface of the grid electrode 18 is also included) and the side of the elastic surface wave element 17 mounted on the bottom plate 16a of the metallic case 16 are coated with an insulating material 19. This insulating material 19 consists of an inorganic material such as SiO2, or an organic material such as polyamide resin, and SiO2, etc. are formed to several mum in thickness by means of vacuum deposition or sputtering. According to said constitution, the electric charge which has charged the surface of the element 17 due to a pyroelectric effect is shut off from air by the insulating material 19, electric discharge to the bottom plate 16a is prevented, also electric discharge to the grid electrode 18 is prevented, and generation of a noise caused by a pyroelectric effect is prevented. |
