The merit of LED (Ligbt Emitting Diode) is long-lifetime，low power consumption and has no body burden. It is available to change from fluorescent lamp into LED for the light source of the lit-sign. But LED is a point light source and its output is low. Then,the luminance value of the luminance distribution on luminous surface of lit-sign will be low and the luminance distribution will be nonuniform.
In this study, it is clear the luminance distribution on the luminous surface of lit-sign by backlight method on using LED.As a results, minimum luminance,average luminance and luminace uniformity ratio on the luminous surface of the lit-sign by using LED is higher than those by using fluorescent lamp.It is also clear the setting configuration of LED to save energy compare with fluorescent lamp.