Patent Application
20110096541
1. Technical Field
The present disclosure relates generally to a plurality of backlit touch buttons and, more particularly, to a backlit touch button assembly used in a portable electronic device.
2. Description of Related Art
A frequently used backlit touch button assembly includes a plurality of light sources, a printed circuit board (PCB), a light guide plate, and a marked strip. The light sources and the light guide plate are positioned between the PCB and the marked strip, and the light sources are positioned around the light guide plate. A surface of the PCB opposite to the light guide plate is coated with a reflecting layer. The marked strip is printed with a plurality of patterns. Light from the light sources is incident upon the marked strip after passing the light guide plate. Other light from the light sources is reflected by the reflecting layer of the PCB, and passes through the light guide plate before reaching the marked strip. The marked strip is thus illuminated by the light sources. The light sources start to emit light when the marked strip is touched by an user.
However, since the light sources are positioned around the light guide plate, the areas adjacent to the light sources are generally brighter than others, resulting in uneven illumination of the buttons.
Therefore, there is room for improvement within the art.
The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Referring to
The reflecting plate 25 defines six optical grooves 253, where each optical groove 253 includes a reflecting portion 2531 and a receiving portion 2533. The reflecting portion 2531 corresponds to the through hole 211 of the circuit board 21. The receiving portions 2533 is configured for receiving the light sources 23. The reflecting portion 2531 is configured to reflect light through the through hole 211. The reflecting plate 25 is adhered to the circuit board 21 via a double-sided adhesive, with each light source 23 received in one corresponding receiving portion 2533, and the through holes 211 opposite to the reflecting portions 2531. It should be pointed out that the reflecting plate 25 may be fixed to the circuit board 21 by means of other securing or fastening methods, such as using screws.
The marked strip 27 includes a main body 271, six marking patterns 273, and a sidewall 275. The main body 271 is non-transparent, and the marking patterns 273 is transparent. The sidewall 275 extends from an edge of the main body 271. The marking patterns 273 are embedded in the main body 271. The marked strip 27 is attached to the circuit board 21 with the marking patterns 273 corresponding to the through hole 211 of the circuit board 21. As such, part of the light from the light sources 23 is incident on the marked strip 27 after passing through the through hole 211, and the other part of the light passes through the through hole 211 after being reflected by the optical grooves 253. Therefore, the marking patterns 273 of the marked strip 27 are sufficiently illuminated by the light sources 23, thereby becoming clearly visible under dark ambient conditions. Contact with the marking patterns 273 by the user is detected by the sensing areas of the circuit board 21 around the through holes 211, and the light sources 23 emit light correspondingly.
Referring to
Using point A of one light source 23 as an example, part of the light from the point A is directly incident on the marking patterns 273 of the marked strip 27 after passing through the through hole 211, and the other part of the light from the point A passes the through hole 211 to reach the marking patterns 273 after being reflected by the optical grooves 253. In detail, the light incident on the first reflecting surface 2534 and the second reflecting surface 2535 is reflected to the through hole 211 and away from the light source 23, thus reducing the brightness illuminated in the area which is adjacent to the light source 23. Light incident on the third reflecting surface 2537 is reflected to the through hole 211 and away from the light source 23, thus enhancing brightness illuminated in the area located farther away from the light source 23. Therefore, the backlit touch button assembly 200 provides improved illumination uniformity. It should be understood that the first reflecting surface 2534 and the third reflecting surface 2537 can intersect the second reflecting surface 2535 at different angles, and have different areas, such that the marking patterns 273 can be sufficiently illuminated by the light sources 23. In addition, the second reflecting surface 2535 can be a roughened surface to further diffuse the light.
In the illustrated embodiment, two positioning poles 255 are formed on opposite sides of the reflecting plate 25, and the circuit board 21 defines two positioning holes 215, correspondingly (as shown in
Referring to
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200910308957.1 | Oct 2009 | CN | national |
