| 摘要 |
An emanation device comprises an emanation material container (10), an em anation section (20) and emanation material level indication means (14,16); wherein, the emanation material level indication means (14, 16) comprises a light source (14), a light detector (16) and control means (not shown), wher ein the light detector (16) is adapted to receive light from the light sourc e (14) when a level of emanation material in the emanation material containe r (10) is at a first level and wherein the light detector (16) is adapted to receive substantially no light from the light source (14) when a level of e manation material in the emanation material container (10) is at a second le vel.
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