| 摘要 |
PURPOSE:To prevent the invasion of refuse or dust or the like into the camera room of an electron microscope by providing a gas source which supplies a dried gas of higher pressure than the atmosphere to the camera room and a control means of gas supply interlocked to the opening and shutting of the door of the camera tube. CONSTITUTION:When a door 21 or 23 is opened an open-shut sensor 45 or 47 of the door sends a signal indicating the open state of the door to a control circuit 49 of gas supply. When the signal indicating the open state of the door is inputted to the said control circuit 49 from at least one of the said sensors 45, 47 the said circuit 49 sends a valve opening signal S4 to the switching valve 33 to open the valve 33. Therefore as soon as the door 21 or 23 is opened dried air 43 of higher pressure than the atmosphere is flowed into the camera room 19 from a compressed air tank 37. As the result, the dried air 43 is ejected from the opened door 21 or 23 to the outside of the camera room 19 to protect the inflow of air from the outside of the camera room 19. Thereby the invasion of dust or the like from outside of the camera room 19 can be prevented.
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