| 摘要 |
PURPOSE:To improve visibility by controlling the protection film of a sensor and the film of an electrode to the best thickness in consideration of optical film thickness. CONSTITUTION:An angle of incidence is about 45 deg., but center wavelength is set to 550nm at the time of 30 deg. incidence so as to utilize interference operation over a wide incidence angle range including a case wherein an observation is made at a 0 deg. angle of incidence. The center wavelength obtained by film thickness calculation is about 570nm on the condition of the 0 deg. incidence. The optical film thickness of an electrode 4 is set to lambda.(2/4) and the the thickness of the protection film 7 is set to lambda.(3/4) on the basis of the center wavelength. When the refractive index is denoted as (n) and the thickness of the film is denoted as (d), the optical film thickness is n.d, so the thickness of the films is found from the refractive indexes 1.87 and 1.63 of ITO and Al2O3 when the wavelength is 550nm, thereby obtaining 0.152 and 0.265mum respectively.
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