公开(公告)号：EP1466305A4

公开(公告)日：2005-03-30

申请号：EP03705668

申请日：2003-01-07

Applicant: PITTWAY CORP

Inventor： LANG SCOTT ,  WISCHSTADT GREGORY

IPC: G01B11/27 ,  G01J1/00 ,  G01J1/08 ,  G01N21/17 ,  G08B17/103 ,  G08B29/20 ,  G08B1/00

CPC classification number: G01J1/08 ,  G01B11/272 ,  G01J1/0418 ,  G01J1/0437 ,  G08B17/103

Abstract: An automatically testable obscuration detector incorporates one of an electrically controllable filter or a mechanically selected filter. Filtered outputs can be compared to expected outputs by control circuitry to automatically assess detector operation.