US Patent 7446274 Keypad assembly for electronic equipment and method thereof

A keypad assembly of electronic equipment includes a plurality of light emitting units, a light guide plate guiding light emitted from the light emitting units, a plurality of key buttons formed on a top surface of the light guide plate and including numeral and character key plates, a plurality of reflection patterns formed on the light guide plate and reflecting light toward the key buttons, a plurality of protrusions formed under the reflection patterns, a switch substrate including a plurality of switches corresponding to the protrusions, a first optical filter layer formed under the numeral key plates and converting the light emitted from the light emitting units into light of various colors according to wavelengths of the light emitted from the light emitting units, and a second optical filter layer formed under the character key plates and blocking violet wavelength light and transmit light having other wavelengths.