METHOD FOR REGULATING LUMINANCE OF TRANSMISSION ILLUMINATION INDICATING BOARD AND TRANSMISSION ILLUMINATION INDICATING BOARD

摘要

To provide a method for controlling luminance of a transmissive board at the moment of transmissive illumination in a short time at a low cost and a transmissive board the luminance of which is controlled by the method. The luminance A-E as the luminance of control object is made the target luminance F by a rough control step of printing ink 2b having a constant light transmittance on a front side or a back side of a part corresponding to luminance as the control object A-E in a transmissive board 1 repeatedly a maximum number times within such a range that the luminances A-E do not exceed the target luminance F, and printing the ink 2b on the front side or the back side of the part by controlling amount of the ink 2b to be printed to a unit area in accordance with a luminance difference between the target luminance F and the control luminance A-E which is not eliminated in the rough control step.