Luminous keyboard and optical module thereof

A luminous keyboard, comprising:

• an optical module comprising:
• a light guide sheet;
• a reflective film on one side of the light guide sheet;
• and
• an optical film on another side of the light guide sheet opposite to the reflective film, the optical film having a mask pattern, the mask pattern defining a light-transparent region, a light-shielding region, and a light modulation region extending from the light-shielding region to the light-transparent region, wherein the light-transparent region allows light to pass therethrough;
• the light-shielding region blocks light;
• the light modulation region partially allows light to pass therethrough and partially blocks light, so that an average light-transmitting rate per unit area of the light modulation region is smaller than that of the light-transparent region and larger than that of the light-shielding region;
• and
• at least one keyswitch disposed over the optical module, the keyswitch including a keycap,
• wherein a vertical projection of the keycap on the optical film at least partially covers the light-transparent region.