| 摘要 |
PURPOSE: To form easily a half mirror that has the same functions as those of a neutral density filter on the rear face of the face plate of a fluorescent display tube. CONSTITUTION: An aluminum membrane having an opening section 521, a non- opening section 522 and a solid section 523 is formed over the entire rear face of a face plate and a dummy half mirror is formed by the opening section 521 and the non-opening section 522. In Figure 2 (a), the opening section 521 and the non-opening section 522 are formed into a lattice form, and in Figure 2 (b), the opening section 521 is formed in a slit form. The transmission factor of the dummy half mirror is determined by the surface ratio of the opening section 521 and the non-opening section 522. That is, by changing the surface ratio between the opening section 521 and the non-opening section 522, the transmission factor of the dummy half mirror can be set freely.
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