公开(公告)号：US3798625A

公开(公告)日：1974-03-19

申请号：US3798625D

申请日：1970-08-13

Applicant: SCI SYSTEMS INC

Inventor： MC MILLIAN L ,  FROHWEIN G

IPC: G01N27/66 ,  G08B17/11 ,  H01J41/08 ,  G08B17/10

CPC classification number: G01N27/66 ,  G08B17/11 ,  H01J41/08

Abstract: An ionization-type gas contamination detector, intended primarily for use as a fire detector, in which a substance which emits predominantly low-energy beta particles is used as an ionizing radiation source in an ionizing chamber. Rapid changes in ionization current, which indicate the presence of a fire or smoke preceding a fire, are detected and an alarm is energized by a rate-of-change circuit in response to such changes. The output of the ionization chamber is amplified, and a level detector energizes the alarm when the amplified chamber output reaches a predetermined level. The output of the amplifier is adjusted relatively slowly to a reference level. In one embodiment, the amplifier output is adjusted to the reference level by the activation of a sample-and-hold feedback loop for a short period of time. In another embodiment, continuous feedback through a circuit with a relatively long time constant provides the desired adjustment. This feature makes the device relatively insensitive to normal atmospheric and environmental changes, while being very sensitive to changes in the level of combustion products in the atmosphere.

Abstract translation: 主要用作火灾探测器的电离型气体污染检测器，其中主要以低能量β粒子发射的物质被用作电离室中的电离辐射源。 检测到电离电流的快速变化，其指示在火灾之前存在火或烟，并且通过响应于这种变化的变化率电路来激励警报。 电离室的输出被放大，当放大室输出达到预定水平时，电平检测器激励报警器。 将放大器的输出相对缓慢地调整到参考电平。 在一个实施例中，通过在短时间段内激活采样保持反馈回路将放大器输出调整到参考电平。 在另一个实施例中，通过具有较长时间常数的电路的连续反馈提供所需的调整。 该特征使得该装置对正常的大气和环境变化相对不敏感，同时对大气中燃烧产物的变化非常敏感。