Light source module using laser as light source

A light source module comprises a plurality of laser light sources, a lens module, a plurality of optical components, and a light guiding plate. The lens module includes a first lens having a rear arced plane and a plurality of second lenses each having a front arced plane, and the second lenses are positioned on the first lens and protruded forwardly from the first lens toward the optical components. The optical components are positioned on light path of light emitted from the laser light sources in sequence and each correspond to one second lens, and the optical components are, except the farthest one from the laser light sources, beamsplitters, respectively and used for reflecting a part of the light emitted from the laser light sources to the second lenses and permitting another part of the light to penetrate therethrough to a next optical component.

BACKGROUND

1. Technical Field

The present disclosure generally relates to a light source module, and particularly to an edge-type backlight module which uses lasers as a light source.

2. Description of Related Art

In recent years, due to excellent light quality and high luminous efficiency, light emitting diodes (LEDs) have increasingly been used as substitutes for incandescent bulbs, compact fluorescent lamps and fluorescent tubes as light sources of illumination devices.

Generally, white LEDs (light emitting diodes) have replaced CCFLs (cold-cathode fluorescent lamps) as a light source for a light source module such as a backlight module. The continuous, whole spectrum white light generated by the LEDs or the CCFLs cannot be effectively used by the LCD (liquid crystal display) which is lightened by the light source module whereby energy is wasted and the color saturation of the image from the LCD is not satisfied.

What is needed, therefore, is a light source module which can overcome the disadvantages as described above.

DETAILED DESCRIPTION

Referring toFIGS. 1 to 3, a light source module100in accordance with a first embodiment of the present disclosure is shown. The light source module100includes a plurality of laser light sources10, a lens module20, a plurality of optical components30, and a light guiding plate40. The light source module100is a backlight module, particularly an edge-type backlight module, for illumining an LCD (liquid crystal display, not shown).

The laser light sources10emit laser light. In this embodiment, there are three laser light sources10including a red laser source11, a green laser source12and a blue laser source13. The three laser light sources10are collimated light sources generating light each having its respective spectrum, whereby white light obtained by a mixture of the light generated by the three laser light sources10can have three distinctive spectra which can be effectively used by the LCD to enable the image of the LCD to have a high color saturation.

The lens module20includes a first lens21and a plurality of second lenses22fixed on the first lens21. The first lens21includes a front flat plane211and a rear arced plane212extending rearwards from the front flat plane211toward the light guiding plate40. The rear arced plane212is curved along a top to bottom (height) direction of the lens module20. The first lens21is elongated and extends along a first direction X of an XY plane which is annotated inFIG. 1. The second lenses22are positioned on the front flat plane211of the first lens21. The second lenses22each include a rear flat plane221contacting the first lens21and a front arced plane222extending forwardly from the rear flat plane221toward the optical components30. The front arced plane222is curved along a left to right (width) direction of the lens module20. An optical axis (not shown) of the front arced plane222extends through a center thereof along a second direction Y annotated inFIG. 1. The first direction X is perpendicular to the second direction Y. In this embodiment, the light source module100includes five second lenses22. The five second lenses22are protruded from the front flat plane211of the first lens21and evenly spaced from each other. Top and bottom of each second lens22are flat.

The optical components30are positioned on a light path of the light emitted from the laser light sources10and uniformly spaced from each other in sequence. Each optical component30is placed corresponding to one second lens22. In this embodiment, the optical components30of the light source module100includes five optical components respectively labeled as30a,30b,30c,30d, and30e, in a direction away from the laser light sources10. The five optical components30a,30b,30c,30d, and30eare optical lens having different degrees of light reflectivity. Each optical component30a,30b,30c,30d, or30eis inclined to the front flat plane211of the first lens21of the lens module20. An angle between each optical component30a,30b,30c,30d, or30eand the front flat plane211is, preferably, 45 degrees. The optical components30a,30b,30c,30d, except the farthest one30efrom the laser light sources10, each are a beamsplitter. The ratios of reflectance/transmittance of the optical components30a,30b,30c,30dare different from each other. The optical components30a,30b,30c,30deach reflect a part of light impinging thereon and allow the other part of the light to be transmitted therethrough. The farthest optical component30efrom the laser light sources10is totally reflective. In this embodiment, a reflectance/transmittance ratio of the optical component30a,30b,30c,30d, or30ecloser to the laser light sources10is smaller than that of a neighbor optical component30a,30b,30c,30d, or30eaway from the laser light sources10. In other words, the reflectance/transmittance ratio of the optical component30a,30b,30c,30d, and30ebecomes larger in the direction away from the laser light sources10. Specifically, the reflectance/transmittance ratio of the five optical components30a,30b,30c,30d, and30eare ⅕, ¼, ⅓, ½ and 1, in the direction away from the laser light sources10. The farthest optical component30eaway from the laser light sources10is a totally reflective lens. The light emitted from the laser sources10are distributed by the five optical components30a,30b,30c,30d, and30eto evenly enter the lens module20. A part of the light striking on the closest optical component30ais reflected to enter the corresponding second lens22, and the other part of the light penetrates the optical component30ato strike the next optical component30b. So do the optical components30b,30c, and30dbefore the farthest optical component30e. When the light strikes on the farthest optical component30e, the light is totally reflected thereby to enter the front arced plane222of the corresponding second lens22. Thus, all the light emitting from the laser sources10can be evenly incident into the lens module20.

Referring toFIG. 2andFIG. 4, the light guiding plate40includes an incidence surface41facing the rear arced plane212, an outputting surface42connecting with and perpendicular to the incidence surface41, and a bottom surface43opposite the outputting surface42and connecting with and perpendicular to the incidence surface41. The bottom surface43is a totally reflective surface with a plurality of protrusions431formed thereon. The light traveling in the guiding plate40is reflected by the bottom surface43to the outputting surface42and extracted to an outside from the outputting surface42to illuminate the LCD. In the first embodiment, the protrusions431each are formed between two serrated recesses in the bottom surface43. In the second embodiment, as shown inFIG. 5, the protrusions431each are formed between two arced recesses in the bottom surface43.

The light emitted from the laser light sources10strikes on the front arced planes222of the second lenses22after being reflected by the optical components30to move along the direction Y. The light beams reflected by the optical components30are evenly distributed along the first direction X whereby the light beam has the same intensity after being refracted by each of the front arced planes222. Then the light is incident into the first lens21and is refracted by the rear arced plane212of the first lens21to be further evenly distributed along the height direction of the first lens21. Accordingly, the light is then uniformly incident into the guiding plate40via the incidence surface41and travels out of the guiding plate40from the outputting surface42after being distributed by the protrusions431of the bottom surface43of the guiding plate40. Benefiting from sufficient reflection and distribution, the light can be uniformly extracted out of the light guiding plate40.

The light source module100further includes two filters50. The filters50are positioned on the light path of the laser light sources10. In this embodiment, the red laser source11and the blue laser source13are parallel to each other, and the green laser source12is perpendicular to the red laser source11and the blue laser source13. The red laser source11is positioned between the blue laser source13and the green laser source12. The light emitted from the red laser source11is parallel to the light emitted from the blue laser source13and perpendicular to the light emitted from the green laser source12. One of the two filters50is a red light filter51, and the other filter50is a blue light filter52. Red light strikes on the red light filter51can be totally reflected. Other color light strikes on the red light filter51can totally penetrate therethrough. Blue light strikes on the blue light filter52can be totally reflected. Other color light strikes on the blue light filter52can totally penetrate therethrough. The red light filter51is positioned at an intersection of the light emitted from the red laser source11and the light emitted from the green laser source12. The blue light filter52is positioned at an intersection of the light emitted from the green laser source13and the light emitted from the green laser source12. The red light filter51is parallel to the blue light filter52. The red light filter51and the blue light filter52both are inclined to the light emitted from the green laser source12. An angle between the red light filter51and the light emitting from the green laser source12is preferably 45 degrees. The light emitted from the green laser source12is able to penetrate through the red filter51and the blue filter52, and then strikes on the optical components30. The light emitted from the red laser source11is reflected by the red filter51and then moves through the blue filter52in a manner parallel to the light emitted from the green laser source12to strike on the optical components30. The light emitted from the blue laser source13is reflected by the blue filter52and then strikes on the optical components30. The light emitted from the green laser source12travels through the red filer51and the blue filter52to strike on the optical components30. The light emitted from the three laser sources10strikes on the optical components30is parallel to each other.