| 摘要 |
A sign board (4000) according to the present invention, comprises a case (140), and a first polarization means (10) and a second polarization means (30) installed in the case (140) such that their front and rear are spaced apart from each other. A light source means (8) is installed towards the rear of the first polarization means (10), and a sign member (28), which comprises a birefringent medium, is installed between the first polarization means (10) and the second polarization means (30). The polarization directions of the first polarization means (10) and the second polarization means (30) are perpendicular to each other. |
