button portions 130 to illuminate function of the button portions 130 selected by the user here the tpu elastic resin 140 which is formed as a type of print film and attached to silicon is enough thin to allow light emitted from the light emitting element 150 to pass through the tpu elastic resin 140 to reach the button portions 130 the light emitting element 150 includes an led or an oled in this case the light emitting element 150 may include a light guide plate lgp in general the lgp refers to an acryl injection molded product assembled in a backlight unit guiding light to liquid crystal within the lcd and it is one of plastic molded lenses uniformly transferring light emitted from a ccfl cold cathode fluorescent lamp to the entire surface of the lcd by including such lgp in the light emitting element 150 light can be evenly transferred from the entire light emitting element 150 the switch 160 is mounted on the rear surface of the light emitting element 150 and installed on the circuit board 170 positioned at a rear side of the switch 160 various signal movement paths are formed on the circuit board 170 and the circuit board 170 receives a signal according to a contact of the switch 160 here the switch 160 may be a dome switch as shown in fig8 in order to reduce the thickness.