Patent ID: 10234619

Abstract:
A backlight module for light-emitting keyboard includes light guide plate having reflective surface, opposing light-emitting surface and plurality of recessed dots located on reflective surface to create optical path of continuous wave-like reflecting portion for facing toward key switch unit in light-emitting keyboard. The spacing between the centers of each two adjacent recessed dots is smaller than or equal to diameter of one single recessed dot. The continuous wave-like reflecting portion exhibits a continuous ring-shaped pattern formed of a series of ring-shaped square waves, triangular waves, sawtooth waves or sine waves and consisting of at least one different cycle waveforms having varying cycle periods, amplitudes or peak-to-peak values that are interleaved in regular or irregular manner. The invention allows adjustment of the frequency and equivalent length of the optical path of the continuous ring-shaped pattern to effectively enhance uniform brightness distribution, improving the average brightness of the light guide plate.