| 摘要 |
PURPOSE:To eliminate noises without using any filter by constituting a surface electrode of a material which transmits infrared rays of wavelength out of the absorption wavelength region of a pellet. CONSTITUTION:The surface electrode is formed of a material which transmits at least infrared rays of wavelength out of the absorption wavelength region of a pellet. The surface electrode 10 of a pyroelectric pellet 9 formed of LiTaO3, for example, is constituted of an Si- or Ge-deposited film of thickness approximately 1,000Angstrom which absorbes the infrared rays in other regions as well as those of wavelength 8- 15mum which are absorbed by the pellet 9. On the other hand, the back surface electrode 11 is constituted of an Ni-Cr deposited film of thickness more than approximately 1,000Angstrom which reflects infrared rays. Then, this is secured to a supporting base 12 through a conductive bonding agent 13 and closed up tightly with a package 14. Thereby, the infrared rays of 8-15mum emitted from a human body are absorbed into the pellet 9 through a transmitting window 6 and the surface electrode 10. Accordingly, an electric charge is generated, and an invasion alarm is sounded. |
