Patent ID: 11860398
Assignee: DARFON ELECTRONICS CORP.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G | IPC F

Claim 0:
1. A backlight apparatus used in an illuminated keyboard, comprising:
a light-guiding plate, having a top face, a back face and a plurality of through holes, each through hole having a respective light incident surface;
a circuit board; and
a plurality of light-emitting devices, all being electrically bonded on the circuit board, each light-emitting device having a respective light-emitting side face and a respective central optical axis and corresponding to one of the plurality of through holes, wherein the circuit board is disposed on the back face of the light-guiding plate such that each light-emitting device is disposed within the corresponding through hole, and that the light-emitting side face of each light-emitting device faces the light incident surface of the corresponding through hole, each light-emitting device emits a light from the light-emitting side face thereof to the light incident surface of the corresponding through hole, and then the light enters into the light-guiding plate;
wherein a first specific through hole of the plurality of through holes has a first optical adjustment surface on the light incident surface thereof, the first optical adjustment surface is one selected from the group consisting of a first concave spherical surface, a first convex spherical surface, a first concave aspherical surface, a first convex aspherical surface, a first Fresnel concave arc surface and a first Fresnel convex arc surface, the first optical adjustment surface has a first curved surface central axis coaxial with the central optical axis of the corresponding light-emitting device,
wherein a first shortest distance between the first optical adjustment surface of the first specific through hole and the light-emitting side face of the corresponding light-emitting device ranges from 0.04 mm to 0.12 mm.