| 摘要 |
PURPOSE:To detect the level of liquid charged in a container with good visibility by providing a hologram dry plate which reflects light according to its incidence angle on the flank of the container and displaying the border line of the light reflected by the dry plate on a display part. CONSTITUTION:Light is emitted by a light emitting diode 11 and its light components C and D which travels in the air in the container 3 are reflected by the hologram dry plate 5 to reach the display part 6. Light components A and B entering the liquid 2, on the other hand, are not reflected by the hologram dry plate 5. Therefore, when the display part 6 is observed in an X direction, light entering the range from the bottom surface of the container 3 to the liquid level position of the liquid 2 is displayed in black and light entering the range from the liquid level position of the liquid to the top surface of the container 3 is displayed in specific color. Variation in the liquid level of the liquid is detected from a shift in the position of the border line of said display part. |
