Backlight apparatus used in illuminated keyboard

A backlight apparatus used in an illuminated keyboard, comprising:

• a light-guiding plate, having a front surface, a back surface and a plurality of first through holes, each first through hole having a respective light entrance face;
• a light-shielding membrane, having a plurality of light-transmitting parts thereon, the light-shielding membrane being disposed on the front surface of the light-guiding plate;
• a light-reflecting sheet, having a plurality of second through holes and a lower surface, each second through hole corresponding to one of the first through holes, the light-reflecting sheet being on the back surface of the light-guiding plate such that each second through hole is aligned with the corresponding first through hole;
• a circuit board;
• a plurality of light-emitting devices, electrically bonded on the circuit board, each light-emitting device having a light-emitting side face and corresponding to one of the first through holes and one of the second through holes, wherein the circuit board is disposed on the lower surface of the light-reflecting sheet such that each light-emitting device is placed in the corresponding second through hole and the corresponding first through hole, and that the light-emitting side face of each light-emitting device faces the light entrance face of the corresponding first through hole;
• and
• a plurality of first translucent glue bodies, each of the first translucent glue bodies corresponding to one of the first through holes, each first translucent glue body being placed on the front surface of the light-guiding plate and surrounding a respective first circumference of the corresponding first through hole to bond the light-shielding membrane thereabove and the light-guiding plate therebelow, each first translucent glue body having a respective first breach, wherein each light-emitting device emits a light from the light-emitting side face thereof toward the corresponding first translucent glue body, the corresponding first breach, and the light entrance face of the corresponding first through hole, and further enters the light-guiding plate, the light is guided by the light-guiding plate and exits from the plurality of light-transmitting parts, and the light-reflecting sheet is used for reflecting the light directed to the light-reflecting sheet.