| 摘要 |
PROBLEM TO BE SOLVED: To develop an inspection process using an easier method without inspecting an image forming device by actually displaying an image. SOLUTION: In an image forming device having an electron source having plural electron emitting elements 13 on a base board in an envelope 5, an image forming member (a face plate 4) oppositely arranged on the base board and a getter material 2 for maintaining a degree of vacuum in the envelope 5, a pressure detecting means 17 is arranged to detect pressure in the image forming device on the basis of a change in a surface color of the getter material 2.
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